Most people do not realize garnets come in a wide variety of gem types and colors, with many cutting options. Garnets are a set of closely related minerals that form a group, resulting in gemstones in ...

Ruby is the July birthstone – and it’s one of the most coveted of gems. The name is derived from the Latin word ruber, meaning “red” – the color of love and passion. Few things catch the eye like the ...

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 ...

Emeralds are formed when chromium, vanadium, and iron are present in the mineral beryl. The varying presence of these three elements gives emerald its range of color. Chromium and vanadium make an ...

A hand-held flashlight reveals the green color of a rough emerald from the Coscuez Emerald mine in Colombia. Photo by Eric Welch/GIA. Emerald is the green to bluish green variety of beryl, a mineral ...

This amethyst crystal is from Namibia. It shows classic quartz crystal shape: a six-sided columnar crystal with a pyramid-shaped termination at the top. Courtesy Daniel Trinchillo, Fine Minerals ...

Reviews the advancements and major trends in laboratory-grown diamonds observed by GIA since 2007. Gemological and Trace Element Characteristics of Cassiterite from Yunling, China Examines gem-quality ...

Figure 1. Pleochroism in a 15 ct tanzanite, as seen with the unaided eye through the crown and the pavilion sides and ends. Photo by Wimon Manorotkul. In describing colored gemstones, the major ...

This large Australian light opal cabochon weighs 117.85 carats. Small play-of-color flashes of orange and green predominate in a pinfire pattern, with spots of a more muted blue over a grayish ...

Top-quality moonstones accent this beautiful platinum and diamond pendant. Moonstone has fascinated designers and gem connoisseurs for centuries. - Courtesy David Humphrey When buyers select ...

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.

2016年にニューヨーク市で行われたアーガイルピンクダイヤモンドテンダーに出品されたダイヤモンド。左から右: 0.64カラットのファンシーディープピンクの楕円形、0.75カラットのファンシーインテンスパープリッシュピンクのトリリアント、0.91カラットの ...