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 ...

Birthstones are a fun, popular and colorful introduction to the world of gemstones. They appeal to audiences around the world regardless of gender, age, nationality or religion. Birthstones carry ...

Greater amounts of colorless sapphire—promoted primarily as diamond substitutes, but also as natural gemstones—have been seen in the gem market during the past decade. In the absence of inclusions or ...

Observations of Oval-, Pear-, and Marquise-Shaped Diamonds: Implications for Fancy Cut Grading Presents findings from observations of oval-, pear-, and marquise-shaped diamonds, laying the groundwork ...