Brilliant cut :
The modern brilliant cut was developed by Marcel Tolkowsky in 1919. It consists of 58 facets (or 57 if the culet is excluded). It is the most popular modern cut because it provides maximized light return through the top of the diamond.
Carat :
The carat (ct) is a unit of mass equal to 2 g. Carat is used for measuring the weight of gemstones.
Onyx :
Onyx is a (banded) variety of chalcedony. The colors of its bands range from white to almost every color. Ony is used to carve Cameos