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Understanding Diamond Polish

January 12, 2010 By marc Leave a Comment

The details of a diamond’s cut are referred to as its finish.  Finish is made up of two categories; Polish and Symmetry.  Polish is the overall condition of the diamond’s facet surfaces and symmetry is the exactness of the shape and placement of its facets.

Diamonds that are well polished will look brighter and will produce sharper light reflection than those that receive a lower polish grade.  Poorly polished diamonds may reduce the light reflected to, into, and out of the diamond even if it has the best proportions possible.

Because of their hardness, diamonds can take a better polish than any other gemstone.  Polish characteristics can be a result of the finishing process or be affected by blemishes created after cutting.  Polishing characteristics are caused by the minute diamond crystals embedded in the polishing wheel used by a diamond cutter to polish the surface of the diamond.  When gem laboratories evaluate polish, the diamond is examined under 10x magnification and the Gemologist will examine the diamond facet by facet.  They look for blemishes that don’t affect the clarity grade.

A diamond’s polish grade and the abbreviation of the polish characteristic are listed on all diamond grading reports.

The GIA polish grades are:  Excellent (E), Very Good (VG), Good (G), Fair (F), and Poor (P)

The AGS polish grades are: Ideal (AGS 0), Excellent (AGS 1), Very Good (AGS 2), Good (AGS 3 and 4), Fair (AGS 5, 6, 7), Poor (AGS 8, 9, 10)

Common polish characteristics

Abrasions (ABR) – minute nicks along the facet junction that look white and fuzzy

Burn mark (Brn) – whitish haze across a facet caused by excessive heat

Lizard skin (LS) – wavy or bumpy area with a transparent pitted texture

Nick (Nk) – small notch on a facet junction with no depth when viewed under 10x magnification

Pit (Pit) – very tiny opening that looks like white dot

Polish lines (PL) – fine groves and ridges left by the polishing process

Rough girdle (RG) – an irregular girdle surface

Scratches (S) – thin tiny white lines across the surface of the diamond that have no depth

Surface grain lines – transparent line that is part of the grain of the diamond

When budget allows, Since 1910 recommends purchasing a diamond for an engagement ring with a polish grade of Good or higher.

To learn more about diamonds, visit our diamond education section

diamonds

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Understanding Diamond Symmetry

January 11, 2010 By marc Leave a Comment

The details of a diamond’s cut are referred to as its finish.  Finish is made up of two categories; Symmetry and Polish.  Symmetry is the exactness of the shape and placement of a diamonds facets and polish is the overall condition of the facet surfaces.

Almost all diamonds on the market today have some minor symmetry problems; which are usually not visible to the unaided eye and have very little effect on a diamond’s appearance and beauty.

To evaluate symmetry, gem laboratories consider the evenness of a diamond’s outline and the size, shape, and placement of its facets.  For grading purposes, two types of symmetry are considered; proportion symmetry and facet symmetry.  Proportion symmetry is the alignment and balance of the diamond’s table, culet, girdle, and angles while facet symmetry is the shape, placement, and presence or absence of the facets themselves.  Proportion symmetry and facet symmetry make up the diamond’s symmetry rating.

Before assigning a symmetry grade, GIA and other gem laboratories look for symmetry variations under 10x magnification.  A diamond’s symmetry grade and the abbreviation of the symmetry characteristic are listed on all diamond grading reports.

The GIA symmetry grades are: Excellent (E), Very Good (VG), Good (G), Fair (F), and Poor (P)

The AGS symmetry grades are: Ideal (AGS 0), Excellent (AGS 1), Very Good (AGS 2), Good (AGS 3, 4) Fair (AGS 5, 6, 7), and Poor (AGS 8, 9, 10)

Common Variations in Proportion Symmetry

Crown angle variation (CV)

Culet off-center (C/oc)

Extra facets (EF)

Girdle thickness variation (GTV)

Misalignment of crown and pavilion facets (Aln)

Misshapen facets (Fac)

Missing facet (MF)

Non-pointing (Ptg)

Out-of-round girdle outline (OR)

Pavilion angle variation (PV)

Table off-center (T/oc)

Table/culet alignment (T/C)

Table and girdle not parallel (T/G)

Wavy girdle (WG)

Excellent and Very Good symmetry grades are rare.  Diamonds with a symmetry grade of Good offer exceptional beauty and are the most frequently purchased diamonds today.  Diamonds with a high symmetry grade are more important in diamonds that have very high clarity grades such as flawless or internally flawless than diamonds with a lower clarity grade.  Symmetry is important for both round brilliant cut diamonds as well as fancy cut diamonds.

When budget allows, Since 1910 recommends purchasing a diamond for an engagement ring with a symmetry grade of Good or higher.

To learn more about diamonds, visit our diamond education section.

diamond symmetry chart

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What is a Fancy Cut Diamond?

January 7, 2010 By marc Leave a Comment

A fancy cut diamond is any diamond shape other than a round brilliant.  The most popular fancy cut diamonds sold today are asscher cut, cushion cut, emerald cut, heart shaped, marquise shaped, oval shaped, pear shaped, princess cut, and radiant cut, but there are many others.

The face up shape of a fancy cut diamond is usually the first thing people notice and the main reason why they are purchased.  Fancy cut diamonds provide a way for you to express your individuality and appeal to those looking for that less traditional look.  Fancy cut diamonds are also a great choice as side stones for a three stone engagement ring or accent stones on a solitaire setting.

Each fancy cut diamond has its own characteristics, so you should take the time to familiarize yourself with each.  Most fancy cut diamonds on the market today are cut using the brilliant cut facet arrangement allowing for the same brilliance, fire, and scintillation of that of the round brilliant cut diamond, but some are cut using step cuts or mixed cuts.  The round brilliant cut features triangular and kite shaped facets that begin at the diamond’s center and go out to the girdle.   A step cut has long, narrow, four sided facets arranged in rows parallel to the girdle on both the crown and pavilion.  Mixed cuts are a mix of both the round brilliant and step cuts.  They can either have brilliant cuts on the crown and step cuts on the pavilion or step cuts on the crown and brilliant cuts on the pavilion.

fancy cut diamond

Some Diamond Terms for Fancy Cuts

Belly – the center area of the side of a heart, marquise, oval, or pear where it curves out slightly.

Head – the rounded end of a pear

Shoulders – the curved edges between the head and belly of a pear

Lobes – the rounded part of a heart

Cleft – the v-shaped part of a heart

Symmetry and length-to-width ratio are important factors to consider when purchasing fancy cuts.  You always want a fancy cut that is symmetrical.  For example, both lobes of a heart should be the same size, both ends of an emerald should be the same width.  Length-to-width ratio determines the shape of a fancy cut.  There are preferred ranges for each shape, but this is also a personal preference.

To learn more about the characteristics of each fancy cut diamond visit our diamond education section.

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