Aside from the right overall proportions and a shape
that suits its owner, a diamond's value and intrinsic beauty are
governed by additional aspects of the workmanship of the diamond
cutter. Namely the diamond polish.
Facets
When looking at diamonds under a microscope, compare the form of each
facet with the ideal forms presented here. For example, a round diamond has exactly
58 facets -- 33 above the girdle, and 25 below.
When looking at actual stones, refer to the diagram above and
try to identify and rate each of the facets. Extra, absent,
or deformed facets decrease the value of the stone.
Girdle
The girdle of a diamond is the middle, or fattest part, of the diamond,
and is measured from "extremely thin" to "extremely thick":
Thin girdles are prone to chipping. Extremely thick girdles hide a
lot of weight, so you end up paying for a heavier diamond that doesn't look that
big. The ideal is an even, medium girdle; this applies to all shapes EXCEPT for the
tip of the pear shape, in which a thick girdle is preferred to make it
less prone to damage. When examining the girdle, make sure that it is well-faceted
and polished, since some diamond cutters will omit this step to save time and to avoid
removing weight from the stone.
Culet
The culet is the bottom part of the diamond, where the pavilion comes
together in a point (refer to the diagram shown above, under "facets").
Culets are rated as "none", "small", "medium", and
"large." The ideal is "none," but if an otherwise perfect stone
has a medium or large culet, it may still be a worthwhile purchase.
