Established in 1931, the Gemological Institute of America (GIA) is the world’s foremost authority on diamonds, colored stones, and pearls. A public benefit, nonprofit institute, GIA is the leading ...

The 75.47-carat Hooker Emerald was worn by Ottoman Sultan Abdul Hamid II, the last sultan of the Ottoman Empire. Photo by Chip Clark, courtesy Smithsonian Institution, National Museum of Natural ...

Despite the commercial value of natural-color diamonds, distinguishing them from treated diamonds remains a significant identification challenge. While some diagnostic visual features exist ...

Studies carried out at the DTC Research Centre have shown that single-crystal CVD synthetic diamond is clearly distinguishable from natural diamond. This article presents information about the CVD ...

Figure 1. These emeralds from Musakashi, Zambia, range from 0.57 to 4.85 ct. The rough samples were polished with one window on each. The faceted sample measures 6.29 × 5.35 × 3.53 mm and weighs 0.97 ...

Figure 1. These 20 completely non-nacreous pen pearls, from the group of 22 samples in this study, are set against a pen shell displaying both nacreous (left) and non-nacreous areas (right). Photo by ...

As a consumer, you will regularly encounter in the marketplace gems that have been treated to change their appearance. A topic that often comes up is whether a particular gemstone is or isn’t treated.

This 3.28-carat Paraíba tourmaline's vivid violetish blue hue rivals the finest sapphires. Because of this tourmaline's rarity, its per-carat price is also likely to rival the price of fine sapphire.

If you were born in the month of June, you are lucky enough to have three birthstones to call your own. June is one of only three months (the others are August and December) that has three birthstones ...

This selection of gems from Ouro Prêto, Brazil, and Russia's Ural Mountains, displays the golden orange to pinkish red color range of precious topaz. The gems range from 7.61 to 14.33 carats in size.

Zircon’s typical greenish blue color has been referred to as zircon blue. - Lydia Dyer, gem courtesy of John Dyer & Co. Zircon is a gemstone that’s not commonly known among jewelry buyers, which is a ...

The greenish blue color observed in some amber from the Dominican Republic and Indonesia is actually fluorescence stimulated by ultraviolet (UV) light. A previous study described the color as ...