Ruby, Emerald & Pearl Set from Jagdamba Pearls

Girdle

The girdle of the diamond is the name for the widest portion of the
diamond. The diamond's diameter is measured at its girdle. The common
practice today is to facet the girdle itself, although these facets are
not included in the diamond's final facet count. As long as the girdle
is not described as extremely or extra thin or thick the girdle has no
effect on the stability of the diamond.

Depth

A diamond's depth is the measured height of the entire diamond.
Measuring from the top of the diamond (the table) to the bottom of the
diamond (the culet), the depth of the diamond helps to set the ratios
for the rest of the diamond's cut.

Culet

The culet is the bottom of the diamond and the diamond's smallest
facet. The culet has tremendous effect on the rest of the diamond in
that a properly formed culet will allow the light that has entered the
diamond to most effectively exit through the diamond's table and
re-enter the eye. A culet that is cut too large can cause a detrimental
effect in the diamond's light display. The overly large culet can cause
the light to leak out from it, thus causing the diamond to appear to
have a hole within it. The culet needs to be small enough, and within
the correct ratio to the rest of the diamond's anatomy to allow the
light to reach it and be refracted back within the diamond and
reflected back out of it. It is not uncommon for a diamond to have no
culet, and instead have the pavilion come to a point. There is no right
or wrong to having or not having a culet.