Following up on Nassau's 1981 article on the technical aspects of heat treating ruby and sapphire, the author reports his personal observations of the actual heat treatment process in Bangkok. He ...

Since Robert Crowningshield's discovery in the late 1950s that diamonds that have been artificially colored by irradiation and subsequent annealing could be identified by their characteristic ...

This article examines the sophisticated techniques and equipment currently used to fashion a polished gem from a rough diamond. The basic manufacturing techniques— sawing, bruting, blocking, and ...

Visit us at the 70 th Bangkok Gems & Jewelry Fair to learn what’s new at GIA and take advantage of quick, convenient gem identification and origin identification services for colored stones at our ...

This 7.19-carat alexandrite was cut to feature its beautiful color change. When the light source changes from daylight to incandescent light, the gem’s color changes from bluish green to reddish ...

Cultured pearls come in different sizes, shapes, and colors. Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most ...

Diamonds have a long history as beautiful objects of desire. In the first century AD, the Roman naturalist Pliny stated: “Diamond is the most valuable, not only of precious stones, but of all things ...

Cubic zirconia can be produced in large sizes and in different colors. These colorless and pinkish purple CZ are, from left to right, 44.49 carats, 29.86 carats and 54.60 carats. Photo: Tino Hammid.

The 330-ct Star of Asia is in the collection of the National Museum of Natural History – Chip Clark, courtesy Smithsonian Institution Traditionally, sapphire symbolizes nobility, truth, sincerity, and ...

Consumers now, more than ever, have a heightened awareness of sustainably and ethically sourced products. The GIA Diamond Origin Report uses scientific evaluation to provide confirmation of a ...

Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes). Diamond clarity refers to ...

Diamond is available in a range of sizes and qualities to fit every consumer's tastes. One of the first things most people learn about diamonds is that not all diamonds are created equal. In fact, ...