Presents a detailed examination of about 800 samples of carbonado diamond from Brazil and the Central African Republic, including possible models for its genesis.

An overview of Summer 2017 issue of G&G.

Provides a visual guide to the internal features of natural, synthetic, and treated sapphires.

Documents a visit to the upper Missouri River and Rock Creek sapphire mining areas.

Demonstrates the importance of this method in identifying diamond treatments, based on the analysis of PL maps acquired from a brownish orange HPHT synthetic diamond.

世界各地から同窓生が支部のイベントに参加し、業界を支援するために全力を尽くします。 さまざまな方法で参加していただくことができます。

同窓生が、2011年に発生した東日本大震災後の大被害を乗り越える中、仲間たちを指導することを決心し、 同窓生同士のつながりを築くのを助けることが、いかに重要であるかを主張します。

A yellow cultured pearl necklace is compared to the work of a producer specializing in freshwater pearls of all colors.

A new source of sapphires is found in the Tigray region of Ethiopia.

A submission to the New York lab yields an unexpected reaction to long-wave UV radiation.

Unique natural conch pearls are studied in the New York lab.

Analysis of a diamond graded Fancy blue revealed a CVD synthetic overgrowth on natural diamond.

Blister pearls attached to shells are seen in both the Bangkok and New York laboratories.

A dichroic inclusion within a quartz crystal is found to be chlorapatite.

A laser manufacturing remnant in a Fancy yellow diamond creates a unique specimen.

A rare mineral is found in a rock crystal quartz host.

A rough aquamarine crystal shows an unexpected phenomenon.

Raman analysis identifies unusual inclusions in quartz.

A synthetic cubic zirconia shows a surprising color change combination under different light sources.

A study of a pink Japanese akoya cultured pearl yields information about the material’s color origin.