As an addendum:
If you use an evaluation chart that shows 1. range of color grades and their compartive percentage values 2. the range of clarity grades and 3. the effect of size on these percentages, a number of facts quicky become clear.
Assuming an American cut:
the percentage drops in color are considerably more rapid in large stones than in small ones. This is a reflection of the fact that the per carat prices of large colorless stones are many times higher than the per carat prices of small colorless stones, whereas the differeces in per carat prices of poor colores for both size categories are small. The rason for this is that the larger the
stone, the more obvious the body color and ther rarer the stone in which no color can be detected. Thus, the larger the stone, the more important color is as a price factor.
In very low color grades, there is very little change in price between grades a letter or two apart.Below the price at which the yellow becomes obvious to the unaided eye, the drop in price from letter to letter is very small. A three carat size, flawless stone
drops 20% from category J to K but only 4% from L to M.
Just a note for some of the posters who have mentioned
broken stones and the fact that they are often brown, grey,
yellow. Even when they have not broken in situ, they often break as they are being cut. This is because there are distortions in
the structure. These give rise to abnormal stresses. Not only
are brown diamonds, grey, etc. not desirable because they are often unnattractive but because buying them is risky as they may
fracture when being cut. |
