Figure 1. Yellow, brownish gray, and near-colorless anorthoclase feldspar from southeast Vietnam. The rough stones range from 96.5 to 144.8 ct and the cut samples from 3.64 to 11.07 ct. Photos by Le ...

At the GJX show, Pillar & Stone (San Francisco, California) offered bright green jade from Guatemala, confirmed to range from jadeite to omphacite, that was highly translucent to nearly transparent.

Pursue your passion Whether you’re taking the next step in your professional journey or starting a new career, GIA courses and diploma programs prepare you for success. We offer the finest gem and ...

ONLINE EDUCATION PAYMENT PLANS Tuition payment plans are available for the online courses listed below with the first installment and a non-refundable $35 plan administration fee due at the time of ...

Figure 1. This gold ring with a phoenix motif features a Neyshabur turquoise (13 × 17 mm), with a 0.02 ct ruby on each side and diamond accents. Courtesy of Taktala Jewelry, Tehran. Turquoise is an ...

Figure 1. This cross section through ancient thickened continental lithosphere and underlying mantle shows the two major depth intervals of diamond formation. The majority of mined diamonds originate ...

Feature Gems & Gemology, Summer 2021, Vol. 57, No. 2 Detection of Color Treatment and Optical Brightening in Chinese Freshwater “Edison” Pearls Chunhui Zhou, Joyce Wing Yan Ho, Sally Chan Shih, ...

Diamonds are the most amazing of gems. Just as amazing, however, is how natural diamonds reach Earth’s surface. Diamonds are formed 150 to 700 km deep in Earth, and are then carried upward in a rare ...

Aquamarine and heliodor are colored by Fe ions, an important coloring agent for beryl. Blue to yellow gem beryl was studied by quantitative spectroscopy and trace-element analytical techniques to ...

Gems & Gemology, Winter 2023, Vol. 59, No. 4 A Unique Petrified Tree Fern from Northeast China Ying Yan, Xiao-Yan Yu, Han-Yue Xu, and Zhi-Rong Xie ...

In November 2022, a parcel of 24 approximately 0.5–1.2 ct spinel crystals, described as cobalt-diffused, were obtained directly from a treater by the research team at GIA in Bangkok. Of these, seven ...

The sample set of 90,000-plus diamonds includes all those submitted to GIA from 2008 to 2016 with pink as a primary color, and also spans the color hue range from red to purple and saturation range ...