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