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The 4 C’s

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The 4 C's

7 Interesting Diamond Factoids

Antwerp’s diamond district is a treasure trove of diamond factoids, diamond history and, of course, diamonds. It is the city which handles nearly 80 percent of the world’s rough diamonds and over 50 percent of the world’s precious stone-quality diamonds. The diamond district in Antwerp is a small area (only a square kilometer) and also holds the Diamond Museum, a world-renowned museum which provides an in-depth look into the diamond industry and its worldwide impact. Here are some interesting factoids about the ever-changing world of diamonds that you probably didn’t know.

  1. Pink diamonds originate from Australia. Research shows that nearly all natural pink diamonds are found in Australia’s Argyle Mine.
  2. Until 1990, De Beers owned 90 percent of the diamond market. And what’s even more ridiculous is that almost all diamond purchases before 1990 put some money into De Beer’s deep pockets.
  3. Many dentist drills are embedded with diamonds. That’s because diamond is virtually unbreakable!
  4. Almost 80 percent of diamonds mined are ground into diamond powder. What’s all that diamond dust for? Most of it is melted into the metals of drills, knives, saws and other metal tools.
  5. The word “diamond” has its etymological roots in the word “indestructible”. Not a bad word linkage for what is known to be the hardest substance on the planet. “Diamond” is a mutation of the Greek word “adamas”, meaning “indestructible”.
  6. Diamonds cut before 1950 have a different shape from most diamonds cut after 1950. Gemologists established the “Antwerp” cut in 1950, in which they found a shallower geometry to cut, which distributed more light and sparkle.
  7. The term “carats” is actually a reference to the diamonds equivalent weight in carob seeds. “Carat” is a derivative of the Greek word for “carob seed”.
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Diamond Fluorescence

Fluorescence is the emission of visible light by a material when ultraviolet light, x-rays, or other forms of radiation stimulate it.  The term “fluorescence” is derived from the mineral fluorite; which is known for displaying intense fluorescent colors.

What is Diamond Fluorescence?

When diamonds with fluorescence are viewed under UV light, they will most often display a blue color.  Diamonds can fluoresce purple, green, orange, yellow, red, or white.  The fluorescence is often seen in patches and diamonds can still fluoresce after the UV light is turned off which is called phosphorescence.  Diamonds with blue fluorescence will have a yellow-green phosphorescence.  Under x-rays a diamond will usually have a blue-white glow.

Certified diamond reports will list whether or not a diamond has fluorescence under a UV light and the strength of the fluorescence.  Fluorescence is not a grade like cut, clarity, or color it is just a description given to further identify the diamond. The GIA categories for fluorescence strength are none, faint, medium, strong, and very strong.  The AGS categories are negligible, medium, strong, and very strong.

What causes Diamond Fluorescence?

Irregularities in the diamond’s atomic structure cause fluorescence. Although the chemical structure for a diamonds contains only carbon, traces of other elements such as nitrogen, boron, or aluminum can be found.  Nitrogen and aluminum create blue fluorescence, a single nitrogen atom will create yellow fluorescence, and two nitrogen atoms with crystal irregularities from radiation will create green-yellow fluorescence.

What is the difference between UV light and Fluorescent light?

UV lighting fixtures emit UV light and fluorescent lighting fixtures emit visible light.  Even though both lights are similar, fluorescent lights are coated on the inside and absorb the UV light emitting only visible light.

Are diamonds with fluorescence less valuable or less desirable?

Many believe the answer to this question is still up for debate and we say it depends on the diamond’s color and strength of the fluorescence.   Diamonds in the near colorless range with strong fluorescence usually sell at a discount and can make the diamond look oily, hazy, or milky.  On the other hand, fluorescence can work in your favor.  Diamonds with strong blue fluorescence in the I and lower color range will make the diamond look whiter in natural light.

Diamonds are beautiful and should be judged by normal light.  A diamond should be selected under the light source it will be worn in.  Do you know anyone that carries around a UV lamp?  When shopping for a diamond for engagement rings, don’t let the word “fluorescence” deter you from looking at the diamond further.  Like color and clarity if the fluorescence is strong you will notice it regardless of lighting.

diamond fluorescence

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Diamond Recutting

Why are diamonds re-cut?  Diamonds can be re-cut for many reasons.  The most common reason, even though diamonds are the hardest material on earth, is to remove chips and breaks.  Diamonds are also re-cut for the following reasons:

To make them look new and more modern – an Old Mine cut can be re-cut into a modern round brilliant (image shown below).  This will add brilliance, fire, and scintillation.  What once was an antique style cushion cut will now be modern and beautiful.

diamond recutting

To make them look antique – opposite of above….take a round brilliant cut and have it cut to an antique style shape.

To improve brilliance – adding additional facets will increase brilliance to any diamond.

To improve the cut grade – changing the diamond’s proportions will increase the cut grade.

To improve the color grade – excess diamond weight can be removed to increase the color grade.

To improve the clarity grade – certain clarity characteristics can be removed or polished away increasing the clarity grade.  It is not impossible to improve a clarity grade from a SI1 to a VS or VVS grade or even flawless.

diamond before

After looking at this list, you may be wondering why diamond cutters don’t just cut diamonds originally to produce the best color, clarity, and cut possible.  The reason – diamond cutters try to retain as much weight as possible from the diamond rough to maximize its value.   Diamond cutting is a skill and cutters need to compromise between beauty and value.  In the end, the value and salability of a finished diamond determines how a diamond is initially cut and whether or not a diamond is worth re-cutting.

When thinking of re-cutting your diamond it is important to discuss your options with a jeweler.  What you see as a dull chipped diamond may be a prized possession to others.  Over the years, diamond cutting and technology has changed.  If you take a look at your grandmother’s diamond you will notice the difference in brilliance, fire, and symmetry.  The round diamonds of today are much more brilliant than those of yesterday.

Why do people re-cut their original stones?

Sentimental value – Many of us get engaged at an early age and purchase the best diamond possible at that time.  Over the years, our budget and taste may change, but some are attached to the sentimental value of their original stone and upgrading is not an option.   Re-cutting is a great option for those holding onto their original stone for sentimental reasons.

Wear and tear over the years – even the hardest material on earth gets worn with age…over time diamond girdles may chip and your table and upper facets may get scratched.  Having your diamond polished will make it look as good as new.

To increase the color and clarity grade – with cut grade being the most important factor when purchasing a diamond often times color and clarity are sacrificed.  Having your diamond re-cut will enhance both.

Never think your diamond is beyond repair.  It’s amazing to see a poorly polished dull looking or damaged diamond re-cut into a beautiful brilliant stone.  In most cases, you will loose some weight off your diamond, so before starting the process be sure to think about all your options carefully.

When discussing options with your jeweler, ask to see an example of what your diamond may look like after it is re-cut.  Place your diamond and the jeweler’s diamond side by side.  This will give you a good idea of what you can expect and will help you decide.

The cost of re-cutting varies from stone to stone.  A diamond that just needs a little polishing will cost much less to repair than a diamond being re-cut for color or clarity.

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How to Choose a Diamond Color

The term “color” in white diamonds actually refers to the lack of color present in a diamond.  Diamonds composed of pure carbon are colorless and extremely rare and costly.  Most diamonds contain nitrogen, boron, or hydrogen all of which impact color.  A majority of white diamonds sold on the market today contain traces of nitrogen, which causes slight shades of yellow or brown.  Small, subtle differences in color can make a substantial difference in a diamond’s value.

Diamond Color Grading System

In a effort to eliminate confusion related to diamond color, the Gemological Institute of America (GIA) implemented the color grading system in the 1950s which is still being used industry wide today.   Diamonds are graded on a scale beginning with the letter D (colorless) and ending with Z (light yellow or brown).   When creating the new color scale GIA chose to start with the letter D as a means of starting over.  Prior to GIA implementing the D-Z scale, other systems all of which were inconsistent and inaccurate, already used the letters A-C, numbers 0-3, and the Roman numerals I-III.

Choosing a Diamond Color

Diamond color is largely a personal preference.  Some people prefer a colorless diamond while others prefer the warmth of a diamond having a trace of color.  If you do not have a specific color choice in mind, you should always choose the highest color grade within your budget.

As mentioned above, diamonds are graded on a scale from D-Z.  Z colored diamonds should not be confused with fancy colored diamonds.  While slight color variations in the colorless and near colorless ranges may not be that noticeable, diamonds graded beyond H may be noticeable to some with the unaided eye.

Diamond Color Grades

Colorless D – F

D – colorless and rare.  D colored diamonds are completely colorless to the unaided eye

E – almost completely colorless.  E colored diamonds have microscopic traces of color which can only be seen by a trained expert.

F – almost totally colorless.  F colored diamonds have small traces of color which can only be seen by a trained expert.  F colorless diamonds are at the end of the colorless range and offer a great value to someone looking for a colorless diamond

Near Colorless G – I

G – nearly colorless and an excellent value for you money.  Color will not be seen with an unaided eye.

H – I – slight trace of color that can only be seen to the unaided eye next to a colorless diamond

Faint Yellow J – M

These diamonds have color that is visible to the unaided eye.  These offer a great value for someone that is not looking for a colorless diamond.

Factors to Consider When Choosing a Diamond Color

Many factors should be considered when deciding on color.   You should always look for a diamond that is as white as possible within your budget.

  • When a diamond is well cut the diamond’s refraction and dispersion will often disguise certain degrees of color and may make a darker diamond appear whiter when viewed with the unaided eye (without magnification).
  • The size of the diamond will also affect the appearance of its color.  Color can easily be seen in larger diamonds as opposed to smaller diamonds.  Often times it is difficult to see color in diamonds under a 1/2 carat with the unaided eye.   Gemologists use magnification to determine the difference in color of two otherwise similar diamonds that may be two or three color grades apart.  In larger size diamonds it does become easier; however while there may be a very fine disparity between one color grade to the next, the cost can be significant.   If a larger diamond is a priority, you should consider sacrificing slightly on color.
  • The shape of the diamond will affect its color as well particularly step cut diamonds such as the Asscher and Emerald that have large open facets and do not display the brilliance of other cuts.  The center of these diamonds display a “window effect” where some of the color in the diamond can appear washed out and make it appear whiter then its actual color grade.  The shallower the cut of the diamond the more apparent this will be.

Fluorescence

One additional factor in grading the color of a diamond is fluorescence.  Fluorescence is the emission of visible light by a diamond when it is exposed to ultraviolet radiation.   Approximately 10% of all diamonds on the market today exhibit fluorescence.  Years ago, these diamonds were referred to as blue white diamonds.  Today, fluorescence on a diamond certificate is divided into five different categories: none, faint, medium, strong, and very strong.  Most diamonds that do fluoresce do so in a blue color; however, yellow and other colors are possible.

Fluorescence can be both a negative and a positive.  In the strong and very strong range a diamond may appear oily or cloudy which will greatly reduce the attractiveness and value of the diamond.  However, diamonds of I color and lower can actually look whiter with some fluorescence which; enhances their value.  Better quality diamonds with fluorescence generally sell at a discount to similar ones without.  The usual reason is not that it is less beautiful, but that the general public is under the opinion that fluorescence is a negative.  It is easier for a jeweler to sell a diamond without fluorescenc  than it is to try and explain it.

To learn more about diamond color, visit our diamond education section

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Diamond Color Chart

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Understanding the Many Shapes of Diamonds

With so many diamond shapes available on the market today, how do you know which one is right for you?  Each diamond shape offers something a little different. The round brilliant cut and the princess cut offer the most sparkle and fire while the emerald cut offers a classic elegant look.

Here is a look at the top 10 diamond shapes for engagement rings sold today.

Round Brilliant Cut Diamond

More than 100 years ago, a Russian Mathematician named Marcel Tolkowsky, who was a member of a large powerful diamond family, calculated the number of cuts necessary to create the “ideal” diamond shape, known today as the brilliant cut.  Since that time, cutters have been using advanced techniques and mathematical calculations to intensify brilliance and fire.

The Round Brilliant (aka brilliant cut) shape diamond is the most popular of diamonds shapes.   It consists of 58 facets and displays the most brilliance, fire, and scintillation of all diamond cuts on the market today.

Asscher Shaped Diamond

The Asscher cut diamond was developed in 1902 by the Asscher Brothers of Holland and is a variation of an emerald cut.  The Asscher cut is a stepped square cut also known as a Modified Square Emerald cut.   This cut offers a small table (largest facet on a stone) high crown (top portion of the stone) deep pavilions (lower portion of the stone), and cut corners.   With its 72 wide step facets it resembles that of an octagon and sparkles like the Round Brilliant.   The recommended length to width ratio for this diamond shape is 1.0 – 1.05 which will provide for a square look.

Emerald Shaped Diamond

The “Emerald Cut” was originally developed for cutting Emeralds not diamonds and this is how it received its name.  The Emerald cut provides for a very elegant classic look and is known for its long lines.   The pavilion (bottom portion of the stone) is cut with large facets to create an optical appearance and because of this clarity, cut, and color are very important factors when considering this cut.  The recommended length to width ratio for this diamond shape is 1.30 – 1.40.

Cushion Shaped Diamond

The Cushion cut diamond is unique with its rounded corners and larger facets and is also known as a pillow cut or candlelight diamond.  The Cushion cut is an antique cut that is a cross between the Old Mine Cut popular in the late 19th Century, early 20th Century and an Oval cut diamond.   This cut provides for a classic look and is not as brilliant as the more modern cut diamonds.  The Cushion has large open facets so clarity and color are important factors when considering this cut.  The recommended length to width ratio for this diamond shape is 1.25 – 1.30.   A ratio between 1.0 – 1.05 offers a square look whereas a ratio greater would offer a more rectangular look.

Heart Shaped Diamond

The Heart shaped diamond is known as the most romantic of all diamond cuts.  The Heart is essentially a Pear shaped diamond with a cleft.   This cut is very distinctive and is beautiful when set.   Symmetry and length to width ratio are very important factors to consider when purchasing this shape.   The recommended length to width ratio for the perfect heart shape is between .90 – 1.10.

Marquise Shaped Diamond

The Marquise cut resembles the shape of a football or classic style boat when viewed from above.  The cutting method used for a Marquise is a “step cut” also known as a “table cut.”  The facets on a “step cut” are cut in steps.  The crown (top portion of the stone above the girdle), pavilion (bottom portion of the stone below the girdle), and table (largest facet on a stone) are cut in rectangular facets.  The Marquise is bright, clear, and has a great deal of sparkle because the facets span the length or width of the stone and decrease, as they get closer to the table.

Oval Shaped Diamond

The Oval is a brilliant cut and is an adaptation of the Round Brilliant.  With its 56 facets it usually looks larger than a round stone of the same carat weight.  It is a great alternative for someone wanting the look of the Round Brilliant, but also looking for something a little different.  The Oval is a classic choice and flatters the shape of the hand as the length of the Oval accentuates long slender fingers.

Pear Shaped Diamond

The Pear is a brilliant cut diamond and is half Oval and half Marquise.  The Pear resembles that of a tear drop pointed at one end and rounded on the other.  An ideal Pear cut has 58 facets offering a display of brilliance and fire.  The Pear is unique and is a great alternative to the round brilliant.

Princess Shaped Diamond

The Princess has sharp uncut pointed corners and with 58 facets are known for their brilliance and fire.  There is no other rectangular or square shaped stone that comes close to the Princess in terms of brilliance.

Radiant Shaped Diamond

The Radiant has the brilliance and fire of the traditional Round Brilliant, but the shape of the Emerald and Asscher cuts.  The Radiant was designed with 70 facets for the maximum amount of brilliance.  It has cropped corners and is often slightly more rectangular over square shaped.

To learn more about diamond shapes and our recommendations for each, visit our diamond shape education section

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Understanding Diamond Proportions: Fancy Cut Diamonds

Fancy cut – any shape other than a round brilliant; Asscher, Emerald, Heart, Oval, Pear, Marquise, Princess, Radiant

When grading fancy cut diamonds often times the overall look of the stone is more important than all the proportion details you would look for in a round brilliant. Color and symmetry are still very important, but your eye and personal taste will ultimately determine if the diamond is beautiful.   For fancy cuts, there is no worldwide consensus about beauty.

There are three main cutting styles (the arrangement of the diamond’s facets) for

Fancy cuts; brilliant cut, step cut, and mixed cut.  The most popular cutting style is the brilliant cut.

Brilliant cut – a cutting style where triangular and kite shaped facets start at the diamond’s center and go outwards towards the girdle (example – Oval shape diamond)

Step cut – a cutting style with long, narrow, four sided facets cut in rows parallel to the girdle on both the crown and pavilion (example – Emerald shape diamond)

Mixed cut – a cutting style that combines the step cut and brilliant cut (example – Princess shape diamond)

 

Table, Crown, and Girdle

Table

For fancy cuts, graders measure the table width and stone width then calculate table percentage.  Brilliant fancy cuts are measured from the belly (slight curving center of the long side of a Pear, Heart, Oval, and Marquise) bezel facets.  Step cuts are measured in the middle of the stone because the facets are not always parallel and this measurement provides consistent results.

The following formula is used to calculate table percentage:  Table width divided by stone width x 100 = table percentage rounded to the nearest one percent.  Large tables are common for fancy shape diamonds.

Crown

Crown angles are estimated for fancy cuts diamonds.  To obtain the estimate, graders look along the length of the stone’s profile.  For brilliants, graders examine the bezel facets at the belly and for step cuts, graders examine the profile of the middle row of facets.

Unlike round brilliant cut diamonds where a numerical value is applied to the crown angle, a fancy cut diamond’s crown angle is listed as acceptable, slightly shallow, very shallow, slightly steep, and very steep.

Girdle

Girdle thickness for fancy cut diamonds is evaluated in the same manner as it is for round brilliants however, allowances must be made.   For example, when evaluating girdle thickness for a heart shape diamond the cleft and point will have a thicker girdle than the rest of the stone because of the shape.

Pavilion Depth

To evaluate pavilion depth, graders consider three main factors; face-up appearance, total depth percentage, and the relationship between crown height to pavilion depth.   To determine a final assessment of the diamond, graders consider all of these things individually then together.

First, graders look at the stone face up to determine the stone’s brilliance.  The appearance will determine if the pavilion is steep or shallow.  If the stone looks glassy or if the girdle’s reflection can be seen at the sides of the table the pavilion is most likely shallow and if the stone looks dark the pavilion is most likely steep.

After evaluating face up appearance, graders consider the total depth percentage.  This is the diamond’s depth from the table to the culet and is expressed as a percentage of the width.

The following formula is used to determine total depth percentage:  Stone depth divided by stone width x 100 = total depth percentage

The normal range for total depth percentage is 55% to 65%.  If the total depth percentage falls outside the range graders will begin to evaluate other proportions.  If the stone is deep, graders will look for a high crown, thick girdle, or deep pavilion.  If the stone is shallow, graders will look for a thin crown, thin girdle, or shallow pavilion.  Note – even if the diamond has a total depth percentage within the normal range it is still important to examine each component of the diamond.

To evaluate pavilion depth, graders look at the profile of the diamond and compare the crown height to the pavilion depth.  A well-proportioned diamond’s pavilion should be approximately 2.5 to 4.5 times the depth of the crown.

Bow-Tie and Pavilion Bulge

The final step in evaluating the pavilion is the bow–tie effect and pavilion bulge.  The bow-tie effect is a dark area across the center of an elongated brilliant cut.  When viewing the diamond face up the bow-tie will be visible in all stones however, this should be faint and not dark.   Pavilion bulge is the outward curve of the pavilion facets on a step cut diamond.  Cutters will sometimes cut the top row of pavilion facets wide and at a steep angle.  This creates a bulge and increases weight, which in turn causes light leakage and can make the stone difficult to set.

Culet Size

Culet size is graded in the same manner for fancy cuts as it is for round brilliants.  In fancy cuts the culet is sometimes elongated so the grader will only consider the culet’s width as a factor in its size.

Shape Appeal (“Eye-pleasing”)

Shape appeal is not the same as symmetry.  Shape appeal is what shape is pleasing to your individual eye.

Symmetry

When determining symmetry all of the diamonds parts are compared to its whole.   Symmetry = balance.  To have good symmetry a diamond’s parallel parts should be the same size and shape from the face up and profile view.  (Example – both lobes on a heart shape diamond should be the same size and shape)

Length to Width Ratio

Length to width ratio is a characteristic of fancy cuts and is an aspect of shape appeal.  Length to width ratio is the relationship between the length and width of the diamond.  Certain ratios are more “eye pleasing” than others.   To calculate the ratio you will need the length and width of the stone.  Once those numbers are determined, you divide length by the width and round to the nearest hundredth.  That becomes the first number in the ratio with the width always being one.

The formula for length to width ratio is as follows:  Stone length divided by the stone width

Example: Using an Oval with a length of 9.00mm and a width of 6.00mm

9.00mm divided by 6.00mm = 1.50

The length to width ratio is 1.50:1

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Learning More on Diamond Carat Weight

Carat is the standard term used for the weight of a diamond and received its name from the seed of a carob tree.   The carob tree, which is native to the Mediterranean region, is an evergreen tree with an edible pod containing seeds.  The carob seeds were used by early diamond traders as counter weights on balancing scales as units of weight for small amounts of diamonds because of their consistent size.  The weight of the carob seed was 200 milligrams and the weight of a carat is exactly 200 milligrams or as it is know today, 0.2 grams.

Diamond Weight and Points

One of the first questions we’re usually asked is “how many carats is it?’ Many believe that the term carat represents the size of the diamond however; carat represents the weight of a diamond.

One carat is divided into 100 points.  So, for example, a quarter carat or 25 point diamond weights .25 carats (cts).   Diamonds weighing over one carat are expressed as carats and decimals.   They are measured to the hundred thousandths of a carat and rounded to a hundredth of a carat.   For example, a 1.25 diamond would be described as one point twenty five carats.

The cost of a diamond is not measured in weight alone.   Several diamonds of the same weight can be priced considerable different.  When calculating the cost of any diamond; clarity, cut, and color are major factors as well.

It is also important to understand that a 2 carat diamond will not look twice the size of a 1 carat diamond.   Since a diamond is three dimensional, the carat weight is dependent on both the diameter and depth.  A 1 carat ideally cut diamond averages approximately 6.45 millimeters in diameter and a 2 carat ideally cut diamond measures approximately 8.15 millimeters in diameter.  This is about 26% more in diameter than a 1 carat however; the price is about 4 ½ times greater.  As diamonds get larger in size they are also more rare and the price increases accordingly.

Weight of Round Brilliant Cut diamonds vs. their size.

Diamonds are always measured in millimeters.  Proportions for ideal cut diamonds shown below.

.25ct                        4.2mm

.50ct                        5.2mm

.75ct                        5.9mm

1.00ct                      6.5mm

1.25ct                      7.0mm

1.50ct                      7.5mm

1.75ct                      7.9mm

2.00ct                      8.2mm

2.50ct                      8.9mm

3.00ct                      9.4mm

4.00ct                    10.4mm

5.00ct                    11.2mm

How big of a diamond should I buy?

Carat weight is a personal preference and is a decision we can assist you with, but ultimately, you will need to decide what is most important to you.   For some, color and clarity are more important than size and customers will sacrifice size to obtain the best color and clarity within their budget.   Others will sacrifice on the color or clarity to get a larger diamond.

Regardless of your choice, as a member of the American Gem Society we will only sell you diamonds that meet our standards for color, cut, and clarity and display brilliantly.

Engagement Ring Budget

Prior to selecting a diamond, we recommend you set a budget.  By doing this first it will allow you to explore various combinations of color, clarity, and size that will not only meet your needs, but will keep you within your budget.

Remember, weight will not always increase the value of a diamond.  When a diamond is improperly cut it may reduce its brilliance.  A shallow cut diamond will have more surface area on the crown and will look bigger than one that is cut deep with more of its weight on the pavilion.  When a diamond is properly cut, regardless of weight, you get the most brilliance, fire, and scintillation which equals value.

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Understanding Diamond Proportions: Round Brilliant Cut Diamonds

A diamond’s proportions and their relationship to each other primarily influence the GIA cut grade assigned.  Grading the cut of a polished diamond begins with accessing brightness, fire, and scintillation.  Every proportion of a round brilliant contributes to its interaction with light.  If one proportion is “off” even slightly, a diamond could receive a lower cut grade.  To understand cut grade it is important to know how proportions are evaluated and their relationships to one another.

Grading Proportions – Crown, Table, and Girdle

(Diamonds are always measured in millimeters)

Average Girdle Diameter

Determining average girdle diameter is the first step in evaluating proportions and is the starting point for comparing the diamond’s other proportions.  To determine average girdle diameter, measurements are taken from one edge of the girdle to the other across the diamond in several locations.   Since no diamond is completely round it is necessary to take several measurements.

Total Depth Percentage

Total depth percentage determines why a diamond is underweight or overweight in relation to its diameter.   After obtaining the diamond’s average girdle diameter the total depth percentage can be calculated.  To determine total depth percentage the diamond is measured from table to culet.

Table Facet and Table Percentage

The largest cut facet on a diamond is the table.   The table facet along with the other facets allows light to enter and exit a diamond.  The size of the table facet is an important factor when determining proportions.  Table size is stated as table percentage, which is a percentage of the diamond’s average girdle diameter.

Star Facet and Star Facet Length Percentage

Star facets extend from the edge of the table toward the girdle.  They are very important to consider when evaluating a diamond’s proportions in relation to the rest of the crown as they affect both brightness and fire.

Crown Angle and Crown Height Percentage

Crown angle and crown height percentage are the two crown proportions that affect the diamond’s appearance.   Crown angle is the angle formed by the bezel facets and the girdle plane while the crown angle height percentage is the distance from the girdle plane to the table expressed as a percentage of the average girdle diameter.

The Girdle

The Girdle of a diamond basically prevents damage and provides an “edge” for setting the stone.  A girdle can be bruted, polished, or faceted.  Girdles should be thick enough to prevent chipping, but not too thick where it adds extra weight to the diamond.  Thicker unpolished girdles can created a grayish reflection in the stone which can be unattractive and a girdle that is too thin can create durability problems as well as issues when setting.

Grading Proportions – Pavilion, Culet, and Finish

The Pavilion

The pavilion facets take the light that enters through the crown and reflect it back giving the diamond its brightness.  The pavilion also takes the light and breaks it up into spectral colors known as fire.

Pavilion dimensions are known as pavilion depth percentage and pavilion angle.   The pavilion depth percentage is the distance from the girdle plane to the culet expressed as a percentage of the average girdle diameter and pavilion angle is the angle formed by the pavilion mains and the girdle plane.

Pavilion Depth Percentage

Estimating pavilion depth percentage is done by looking at the reflections seen through the diamond’s table which is most commonly done by rocking the diamond back and forth.   The pavilion facets serve as a mirror reflecting an image to the table.  The reflection should look like a round shape centered on the culet under the table.  It can appear grayish or black in color.  The most common preferred pavilion depth percentage is 43.5%.  Diamonds with a deep depth percentage will appear dark in the center.  Diamonds with a shallow depth percentage will have a grayish ring shape under the table.

Pavilion Angle

Usually, the greater the pavilion depth percentage is the steeper the pavilion angle will be.  Pavilion angles that are very shallow (less than 37.4 degrees) or very steep (more than 44.0 degrees) will have negative effect on a diamond’s appearance.  Steep angles will create a dark area under the table while shallow angles will create an unpleasant reflection under the table.

Culet

The culet is a facet located on the bottom of a diamond parallel to the table and its purpose is to prevent chipping on loose diamonds.  The diamond’s culet should be just big enough to prevent chipping, but if it is too large it will appear as a black spot through the table.   Not all diamonds will have a culet.

To learn more about the grading proportions of a round brilliant, click here

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Diamond Shopping: What You Need to Know About Diamond Clarity

Determining which clarity of diamond to select can feel a bit like shopping for the Emperor’s New Clothes. A diamond free from all natural inclusions will command a much higher price than one that shows the telltale signs of “nature’s fingerprints.” The bottom line is, you will pay much more for things you can’t see!

Flawless diamonds are very rare. Most diamonds will contain what experts call inclusions. These can be microscopic carbon crystals, tiny fissures in the crystal structure, or just a small pinpoint or cloudy spot. Clarity is an important criterion in diamond selection because internal inclusions may affect how the diamond reflects light back to the eye. Keep in mind that most clarity characteristics in stones graded SI-1 or higher will only be visible under magnification. Still, a one and a half carat diamond of good color with only slightly visible internal inclusions may sell for $10,000.00-$12,000.00. But if you are lucky enough to find even an internally flawless diamond of comparable color and size, expect to pay upwards of $16,000.00.

Diamonds with a clarity grade of SI-2 or lower may have natural characteristics that can be seen without the aid of magnification. If a flawless diamond is beyond your budget, consider the following: inclusions are observable evidence that you are buying a natural diamond. Clarity characteristics can add personality to a diamond and make it easy to identify. Not all clarity characteristics are negatives. Imagine a gentleman rejecting Marilyn Monroe on account of the distinct beauty mark on her face!

Once you determine your budget, you will find an enticing array of diamonds to choose from. Understanding how clarity affects a diamond’s price and performance will give you the necessary knowledge to make a smart buying decision, one you will be happy with for years to come.

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Buyers Guide: How To Purchase Diamonds

Buying a diamond should be a great experience and one that is not confusing or overwhelming.  Like any other large purchase you make, education and knowledge is key.  Before purchasing your diamond make sure you have at least a basic understanding of the 4Cs, diamond shapes, diamond terminology, and what to look for on a diamond grading report.  This will prepare you to ask the right questions and will give you the confidence that the decision you make is the right one for you.

The 4Cs of Diamonds: Cut, Clarity, Carat Weight, Color

Diamond Cut

Of the 4Cs, Gemologists believe that cut has the greatest influence on a diamond’s beauty.  Cut is the factor that determines the diamond’s fire, sparkle, and brilliance.   Diamonds have a unique ability to effectively manipulate light.  This unique quality can only be realized with an extremely high level of accuracy during the cutting and polishing process.  Where nature dictates the uniqueness of color and clarity, humans affect the cut.  While cutting diamond rough, cutters must not only consider the proportions of a diamond, but also the craftsmanship of overall symmetry and polish as well.

A diamond’s brilliance comes from light entering the crown and reflecting from one facet to another and returning back out the crown.  A diamond that is cut too shallow or too deep will not reflect light properly and the diamond will not be as brilliant as a diamond with an excellent cut.

Diamond Clarity

Clarity refers to the absence of clarity characteristics in the diamond. The GIA clarity scale consists of 11 grades ranging from flawless to included.  When determining a diamond’s clarity grade, GIA considers the size, nature, color, position, and quantity of clarity characteristics under 10x magnification.  The lesser the number of inclusions or blemishes a diamond has the higher clarity grade it will receive.  A diamond with no inclusions using 10x magnification will be considered flawless and is very rare and more costly.

Inclusions

An inclusion is a clarity characteristic either totally enclosed in a polished diamond, reaching or extending into it from the surface, or one that is caused by treatments or the cutting process.  Note – Inclusions caused by treatments or the cutting process may not always be documented on the diamond certificate.

Blemishes

A blemish or external clarity characteristic is on the surface of the diamond only and can be caused by wear, the cutting process, or may be a result of the diamond’s crystal structure.   Blemishes play a lesser role than inclusions do when determining the clarity grade, but may affect the polish grade.

GIA Clarity Grades

FL – Flawless – no blemishes or inclusions under 10x magnification.

IF – Internally flawless – no inclusions and only very minor surface blemishes.

VVS1 and VVS2 – Very, very slightly included – very, very small microscopic inclusions extremely difficult to see under 10x magnification.

VS1 – Very slightly included – very small microscopic inclusions difficult to see under 10x magnification.

VS2 – Very slightly included – very small inclusions somewhat easy to see under 10x magnification.  These diamonds represent a good value to someone looking for a high quality diamond, as the very small imperfections do not affect the beauty of the diamond.

SI1 – Slightly included – small inclusions that are easy to see under 10x magnification. This clarity is an excellent choice for someone looking to stay within a budget, but wants a diamond that will look as good as a higher clarity diamond except when viewed under magnification.

SI2 – Slightly included – small inclusions that are visible under 10x magnification. Depending on their location within the diamond, they may sometimes be visible to the unaided eye without magnification.  SI2 diamonds are attractively priced and typically no visible difference can be seen without magnification.  If you are interested in an SI2 diamond and would like us to personally verify if it is eye-clean, please give us a call at 1-800-979-1910.

I1* and I2 – Included – imperfect with inclusions that are obvious to the unaided eye and may affect the diamond’s durability.

I3* – Included – imperfect with inclusions that are extremely obvious to the unaided eye and pose a definite threat to the diamond’s durability.

*At Since1910.com, we do not sell I1, I2, and I3 clarity diamonds.

Diamond Carat Weight

Carat weight refers to the size of the diamond.  Carat is the standard term used for the weight of a diamond and received its name from the seed of a carob tree.  The carob seeds were used by early diamond traders on scales as units of weight for small amounts of diamonds because of their consistent size.  The weight of the carob seed was 200 milligrams and the weight of a carat is exactly 200 milligrams or as it is know today, 0.2 grams

Many believe that the term carat represents the size of the diamond however; carat represents the weight of a diamond.  One carat is divided into 100 points.  So, for example, a quarter carat or 25 point diamond weights .25 carats (cts).   Diamonds weighing over one carat are expressed as carats and decimals.   They are measured to the hundred thousandths of a carat and rounded to a hundredth of a carat.   For example, a 1.25 stone would be described as one point twenty five carats.

The cost of a diamond is not measured in weight alone.   Several diamonds of the same weight can be priced considerable different.  When calculating the cost of any diamond, clarity, cut, and color are major factors as well.

Diamond Color

Color refers to the absence of color in the diamond.  Diamonds composed of pure carbon are colorless and extremely rare and costly.  Most diamonds contain nitrogen, boron, or hydrogen all of which impact color.  A majority of white diamonds sold on the market today contain traces of nitrogen, which causes slight shades of yellow or brown.  Small, subtle differences in color can make a substantial difference in a diamond’s value.

In a effort to eliminate confusion related to diamond color, the Gemological Institute of America (GIA) implemented the color grading system in the 1950s which is still being used industry wide today.   Diamonds are graded on a scale beginning with the letter D (colorless) and ending with Z (light yellow or brown).   When creating the new color scale GIA chose to start with the letter D as a means of starting over.  Prior to GIA implementing the D-Z scale, other systems all of which were inconsistent and inaccurate, already used the letters A-C, numbers 0-3, and the Roman numerals I-III.  It is important to note that diamonds at the end of the color range with a noticeable yellow tinge are not considered fancy yellow color diamonds.

Factors to Consider When Choosing a Diamond Color

  • When a diamond is well cut the diamond’s refraction and dispersion will often disguise certain degrees of color and may make a darker diamond appear whiter when viewed with the unaided eye (without magnification).
  • The size of the diamond will also affect the appearance of its color.  Color can easily be seen in larger diamonds as opposed to smaller diamonds.  Often times it is difficult to see color in diamonds under a 1/2 carat with the unaided eye.
  • The shape of the diamond will affect its color as well particularly step cut diamonds such as the Asscher and Emerald that have large open facets and do not display the brilliance of other cuts.  The center of these diamonds display a “window effect” where some of the color in the diamond can appear washed out and make it appear whiter then its actual color grade.  The shallower the cut of the diamond the more apparent this will be.

Diamond Shapes

Diamond shape is the basic outline of the diamond.   Here are some popular shapes sold today.

Round Brilliant is the most popular.  It consists of 56 to 58 facets and displays the most brilliance, fire, and scintillation of all diamond cuts on the market today.

Asscher is a stepped square cut also known as the modified square emerald cut.  It consists of 72 facets and resembles the shape of an octagon.

Cushion is not as brilliant as many of the more modern cuts, but has a classic romantic look that definitely stands out in a crowd.

Emerald is a cut that provides a very elegant classy look and is known for its long lines.  The pavilion is cut with large rectangular facets to create an open effect or optical appearance.

Heart is known as the most romantic of all shaped diamonds.  The heart consists of 59 facets and is essentially a pear cut with a cleft at the top.

Marquise resembles the shape of a football when viewed from above.  The marquise is bright, clear, and has a great deal of sparkle.

Oval is an adaptation of the round brilliant and usually looks larger than the round brilliant of the same carat weight.

Pear is half oval and half marquise.  The pear has 58 facets and displays the brilliance, fire, and sparkle of the round brilliant.

Princess is square shaped with uncut pointed corners.  The princess has 58 facets and is known for its brilliance, fire, and sparkle.

Radiant has 70 facets and has the brilliance and fire of the round brilliant.  The radiant is square/rectangle in shape with cropped corners.

Diamond Certificates

A diamond certificate (aka – diamond plot, diamond grading report) is a document certifying a diamond is genuine and is created by a group of gemologists after the diamond is carefully evaluated.  The report contains information such as carat weight, color, clarity, proportions, and a cut grade for round diamonds.   The certificate also contains a “blueprint” of the diamond’s clarity characteristics.

To understand all aspects of the diamond grading report, click on the GIA link below:

http://www.gia.edu/lab-reports-services/diamonds/diamond-reports/index.html

To understand all aspects of the diamond anatomy, click on the GIA link below:

http://www.diamondcut.gia.edu/05_diamond_anatomy.html

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