CARLSBAD, Calif. – January 29, 2025 – GIA field gemologists recently completed their one-hundredth expedition, adding to the Institute’s unrivaled store of independently verified gemological ...

Two dark brownish red faceted stones, recently submitted to the GIA Gem Trade Laboratory for standard origin-of-color reports, were found to be treated synthetic diamonds. This conclusion was based on ...

Pietersite has been described as a brecciated variety of tiger’s-eye. This study examined pietersite specimens from Namibia and China (the main sources) using powder X-ray diffraction, optical ...

クラリティに関するプロット図付きの完全な4Cの評価。セットされていないDからZのカラー範囲の天然カラー ダイヤモンドで、重量は0.15カラット以上のもののみにご利用いただけます。

Jade is one of the most misunderstood gemstones. It is actually two separate materials: jadeite and nephrite. Together, these materials have more simulants than most other gems. Thus, it is important ...

Vivid blue, green, and purple-to-violet cuprian elbaites, renowned in the gem trade as “Paraíba” tourmalines, continue to be recovered in small amounts from northeastern Brazil. Since the initial ...

Figure 1. This alexandrite cabochon appears brownish green in fluorescent light (left) and brownish purple in incandescent light (right). The cabochon shows chatoyancy under both forms of illumination ...

Although conventional wisdom has been that irradiation will not alter the color of garnets, exposure of some colorless to pale-hued African grossulars to either 60 Co or 137 Cs gamma rays turns them ...

Metrology, the science of measurement and its application, plays a critical role in the accuracy of GIA’s research and laboratory services. The metrology team closely monitors the performance of ...

A new synthetic emerald grown in Western Australia is now commercially available as faceted stones. Infrared spectra revealed the presence of water, thereby confirming that these synthetic emeralds ...

This 376.85-carat tourmaline was carved by O. Hansen, using the colors of the tourmaline as part of the design. - Chip Clark, courtesy Smithsonian Institution, National Museum of Natural History ...

加利福尼亚州卡尔斯巴德 – 2025 年 1 月 29 日 – GIA 实地宝石学家最近完成了第 100 次考察，进一步丰富了研究院从世界各地彩色宝石开采地收集而来的独立验证宝石学信息。 在此次前往肯尼亚 ...