Diamond Grading

Written May 3, 2008 by David Barth, based on information provided by Gassan Diamonds, an Amsterdam Diamond company, Gassan Diamonds, email info@gassandiamonds.com.

Carat

Carat is the weight of a diamond. Generally, the heavier a diamond, the more expensive it is, all other criteria being equal. One carat equals 0.2 grams. One carat represents 100 points. One half carat is 50 points.

Color

The most sought after color is white, actually, the absence of color. Diamond companies often refer to colors differently. Gassan Diamonds uses the following color descriptions, from high value to low:
River (white)
Top Wesselton
Wesselton
Top Crystal
Crystal
Top Cape
Cape
Yellow

Clarity

A diamond with perfect clarity has no carbon (dark spots) or fractures (cracks). The range described by Gassan Diamonds shows the greates value at the top of the list (Perfect), to the lowest value at the bottom (Pique 3).
Perfect (no carbon [dark spots] or fractures [cracks])
The following imperfections cannot be seen by the naked eye and require a loup to be identified:
V.V.S (Very, very, small dark spots or fractures)
V.S. (Very, small dark spots or fractures)
S.I.1
S.I.2
Pique 1
The following imperfections can be seen by the naked eye:
Pique 2
Pique 3

Cut

The type of cut can affect the value of a diamond, but generally, a stone will be cut to reduce the loss of material as much as possible. A poorly cut diamond does not refract light as well as a well-cut diamond.
A round cut loses 50 percent of the original diamond material from the rough stone.
Generally, the more facets, the higher the value. Most stones have 57 facets. Stones with 121 facets are more valuable. The most valuable stones are laser-inscribed to identify them.
Gassan 121 (a round cut with 121 facets)
Brilliant (a round cut with 57 facets)
Princess-cut (square with rounded corners)
Pearshape
Emerald-cut (rectangular with squared-off corners)
Baquette (rectangular cut)
Marquise (oval, pointed at both ends)
Heart-shape
Square-cut

Acknowledgements to Gassan Diamonds B.V., Nieuwe Uilenburgerstraat 173-175, 1011 LN Amsterdam, Holland. Telephone +31(0)20-6225333, FAX +31(0)20-6246084, email info@gassandiamonds.com, web site www.gassandiamonds.com.