The precision with which a diamond
is the cut is the most critical factor in releasing its
"fire" and "brilliance". Since it
is the only factor that humans can control, it may be
the most important of the 4C's.
Fancy colored diamonds cut to the most ideal and accurate
proportions, it may achieve maximum brilliance. A good
cut gives a fancy diamond its sparkle and helps to bring
out the most intense color possible.
When cutting color diamonds, the cutter have to consider
its inclusions, which may help enhancing the diamond's
color. Facets and angles also give color to a diamond,
so the cutter must think about what shape would bring
out the stone's best color.
An "ideal cuts" for colorless diamonds may not
indicate as ideal for a fancy color stone. Colorless diamonds
often cut into round shape to achieve maximum brilliance,
among fancy color diamonds square radiants and ovals are
the most prevalent.