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

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