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.

Greenish yellow to yellowish green HPHT-treated diamonds exhibited highly saturated body color, well-defined brown to yellow octahedral graining, and visual evidence of heating, among other ...

Peer Reviewed Gems & Gemology, Spring 2009, Volume 45, No. 1 Hackmanite/Sodalite from Myanmar and Afghanistan David Kondo and Donna Beaton ...

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

ABSTRACT Aquamarine and heliodor are colored by Fe ions, an important coloring agent for beryl. Blue to yellow gem beryl was studied by quantitative spectroscopy and trace-element analytical ...

A gemological investigation into natural moldavite and its more recent imitations.

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

Learn more about what causes a diamond to chip, and 8 tips on how you can avoid chipping your diamond.

Natural pearl identification is one of the critical problems in pearl research. The DNA study of pearly mollusks and oysters facilitates solving this problem. To fulfill this goal, GIA sent a group ...

Learn about the differences – and similarities – between natural and laboratory-grown diamonds, and how GIA’s researchers and grading laboratories can tell the difference ...

Western Boundary, Sakaraha to Bezaha: The western boundary links Sakaraha, south of the Fiherenana River, and Bezaha, on the Onilahy River. West of that the geology is dominated by limestone-, basalt- ...

Diamonds from the Deep Gems & Gemology, Summer 2019, Vol. 55, No. 2 Kimberlites: Earth’s Diamond Delivery System Karen V. Smit and Steven B. Shirey ...