Gemstone Glossary

Radiant cut

Cut for octagonal stones similar to the emerald cut in outline but with a facet alignement similar to the brilliant cut, developed by the american diamond cutter Henry Grossbard.

Refractive index

Abbr. R.I., important feature in gemstone identification, the sine-relation of incident ray and refracted ray (refracted rays in doubly refractive materials).


Optical instrument for the measurement of the refractive index

Rose cut

Round, facetted stone without pavilion and 3 to 48 crown (upper part) facets