A maze-like pattern is observed in spinel from Vietnam.

A precipitation of an unidentified mineral creates a complex moiré pattern in a fissure of a purple spinel.

Explores eclogitic diamonds, which make up a significant portion of the gem diamond market, and what they reveal about Earth’s dynamic processes.

The Carlsbad laboratory recently had the chance to examine a 4.60 ct cushion-cut zircon with truly unusual color behavior.

Creative faceting highlights an octahedral-shaped cloud inclusion in a 2.01 ct diamond octahedron.

The Tokyo lab examined a stunning double cat’s-eye emerald whose chatoyancy was created both by its cut and its inclusions.

Each level of the vertical Hidden Gems exhibit offers a different theme at the San Diego Natural History Museum.

Copper-bearing gem tourmaline, known as Paraíba tourmaline after the location of its original discovery, is prized for its vivid blue to green color. This article explains GIA’s use of quantitative chemical analyses to distinguish samples from Brazil, Nigeria, and Mozambique.

An emerging corundum deposit in northeastern China is discussed.

At the GIA Carlsbad laboratory, the authors recently examined a cabochon of “bloodshot” iolite (containing red, eye-visible platelets of hematite) intergrown with a sunstone.

This is the second part in a three-part series on the origin of color in gem materials.

The Hong Kong laboratory recently examined a Burmese star ruby incorporating a significant amount of bismuth glass.

A CVD laboratory-grown diamond with a fraudulent GIA inscription is submitted to the Antwerp lab.