Diamond Blemishes Defined

Last week, we talked about internal characteristics, or inclusions, and identified some of the most commonly seen ones. Today, we take a closer look at external characteristics, or blemishes, which are confined to the surface of a diamond.

The plotting diagram on a GIA Diamond Grading Report identifies the location of blemishes by using either green or black symbols (internal characteristics are denoted in red or a combination of red and green). A Key to Symbols lists the characteristics present.

Please remember that these images are magnified to provide you with closer detail, so don’t expect all clarity characteristics to look exactly like the pictures!

	Abrasion A series of minute nicks along the facet junctions of a fashioned diamond; gives the edges a white or fuzzy appearance.
	Extra Facet A facet that’s not required by the cutting style, placed without regard for the diamond’s symmetry; most often found near the girdle. Courtesy K.R. Gems & Diamonds International.
	Lizard Skin Wavy or bumpy area on the surface of a polished diamond.
	Natural A portion of the original surface of a rough diamond left on a fashioned stone; usually on or near the girdle. Courtesy of Gary Roskin, G.G., F.G.A.
	Nick A small notch on a facet junction with no readily apparent depth at 10X, usually along the girdle edge or at the culet. Courtesy of Gary Roskin, G.G., F.G.A.
	Pit A small opening that looks like a tiny white dot. Courtesy of Gary Roskin, G.G., F.G.A.
	Polish Lines Fine parallel grooves and ridges left by polishing; can occur on any facet but do not cross facet junctions; transparent or white.
	Burn Mark Hazy surface area that results from excessive heat during polishing; also called a burned facet.
	Rough Girdle Irregular or granular girdle surface.
	Scratch A thin, dull, white line across the diamond’s surface; shows no apparent depth at 10X.
	Surface Graining Similar to internal graining, except it appears on the surface; results from irregularities in crystal structure.