Blocker

A diamond cutter who specialises in placing the first 18 (main) facets on a brilliant cut diamond (17, where there is no culet). On the crown he places the table and eight bezel facets (or the four bezel and the four top corner facets). With the four facets above and four below, the diamond is called a "Four-Square" or a "Cross": with the eight crown and eight pavilion facets, the term "Eight-Square" is applied. Also known as the lapper, or cross-cutter.

 round brilliant cut diamond