A highly saturated purplish pink to red pezzottaite from a new deposit in Madagascar is encountered in Tucson and tested by GIA researchers.

A chemical and spectroscopic comparison of two purple gem spinel samples, one of them the first reported example of a spinel with a saturated purple color caused predominantly by chromium and cobalt.

GIA ensures accurate gemological measurements across its global laboratories through rigorous metrology practices, including systematic instrument calibration, validation from traceable standards, and ...

CARLSBAD, Calif. – June 2, 2025 – Beginning later this year, GIA (the Gemological Institute of America) will start using descriptive terms to characterize the quality of laboratory-grown diamonds and ...

Diamonds have a long history as a premier gemstone—a natural consequence of their beauty, rarity, and superlative physical properties such as extreme hardness. Diamonds that are mined for use as ...

Zambia is considered the world’s second most important source of emeralds by value (after Colombia). The deposits are located near the Kafubu River in the Ndola Rural Restricted Area. Emeralds have ...

GIA’s Bangkok laboratory encounters two phenomenal gems while examining a parcel of emeralds from Pakistan.

A wide range of Guatemalan jadeite jade in blue, green, and lavender hues was offered at the 22nd Street show in Tucson.

The quality and size of this 4.04 ct CVD-grown diamond ring demonstrate the advancing technology in laboratory-grown diamonds.

GIA researchers report on a new nickel-diffusion treatment used to modify color in spinel and present criteria for identification.

This installment of “Colored Stones Unearthed” explores inclusions in gems—how they form, how they are studied, and what they mean for gemologists and geoscientists.

New York laboratory receives resubmission of HPHT-treated diamond that changed from a dark yellowish brown to a deep yellow-orange during treatment.