BRILLIANT HAVING PLURAL RINGS OF FACETS, EACH HAVING AN ODD NUMBER OF FACETS

摘要

A brilliant gem having upper and lower facets which are inclined to a girdle plane and formed by lateral surfaces of pyramids. The angle between the lower facets and the girdle plane ranges from 37 DEG to 45 DEG , and is selected such that emerging light is dispersed in a dispersion angle of from 1 DEG 20 minutes to 12 DEG 57 minutes. The gem is also provided with a second plane parallel to the girdle plane, and contains an odd number of upper and lower facets in a ring of facets circling the gem.