Optical Effects of Phenomenal Cabochons
Learn how the structure, inclusions and properties of some gemstones interact with light to create unusual visual effects.
GIA's Gübelin Gem Project: Various Gems, Barite - Cuprite
Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.
Spring 1991 G&G Lab Notes
This section, from the Spring 1991 issue of Gems & Gemmology, is a compilation of interesting finds from GIA’s laboratories.