Major rock units of the Neyshabur mine are divided into three groups: volcanic, subvolcanic intrusions, and hydrothermal breccia (Ghiasvand et al., 2017). Although the volcanic rocks of trachyte and ...

This 32” x 20” wall chart presents GIA’s system for classifying pearl quality according to the seven factors of size, shape, color, luster, surface, matching, and nacre.

Consumers have more options than ever when it comes to buying diamonds. In addition to jewelry retailers, you can shop from your computer, tablet or smartphone. Many of the same considerations apply ...

Explore diamond history, research, quality factors, and more in the GIA Gem Encyclopedia.

Part 4 of 5 in the series: Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond). This article digs deeper into cutters’ choices and explores additional factors used in the trade ...

ABOUT GIA An independent nonprofit organization, GIA (Gemological Institute of America), established in 1931, is recognized as the world’s foremost authority in gemology. GIA invented the famous 4Cs ...

Explore pearl history, research, quality factors, and more in the GIA Gem Encyclopedia.

This exhibit features 50 exquisite gemstone jewelry pieces and objects from India on loan from a private collection. Never seen in public, these pieces - including several from the magnificent Mughal ...

Field reports, videos, photography, and firsthand accounts from mines and industry hot spots around the world.

The quarterly journal of the Gemological Institute of America.

colored stone research The microscope is one of the most important tools for a careful gemologist. Unbeknownst to the casual observer, there exists a fascinating and visually stunning microscopic ...

Within a short time, 90 more claims appeared in the same 20-square-mile area. No one was quite sure what the beautiful crystals were, but everyone wanted to lay claim to the profits they were certain ...