A synthetic diamond seen in the Carlsbad lab is the largest faceted lab-grown diamond examined by GIA.

Irradiated CVD-grown diamonds are examined in the Carlsbad lab.

A sapphire cabochon with an unusual appearance is seen at GIA’s Tokyo lab.

Over the last decade, the production methods used to create synthetic diamond melee have improved substantially, along with the quality of the specimens themselves.

Crassostrea virginica, the so-called Eastern or American oyster, is a commercial seafood widely distributed along the east coast of the United States to the Gulf of Mexico.

Lotus Gemology receives submissions of star stones on a regular basis, so when we first saw the specimen shown here, it appeared to be one among many of our usual stones to test.

Aesthetically pleasing inclusions are found in topaz from Pakistan’s Shigar Valley.

A black star sapphire produced from eastern Thailand, showing both golden and silver rays, is studied at GIA’s Bangkok lab.

For the first time, wurtzite is found as an inclusion in gem material.

A Medusa quartz from Paraíba, Brazil, hosts a surprising inclusion.

A diamond examined in the Carlsbad lab shows chameleon coloring in an unusual pattern.

Seldom-seen inclusions are found in a host material that is rare in its own right.

A yellowish green specimen with horsetail-like inclusions is found to be glass rather than demantoid garnet.

A project coordinated by GIA and the NGO Pact provides a valuable educational tool to women miners in Tanzania.

A look at the color zoning exhibited by the largest HPHT-treated blue diamond graded by GIA.

recently identified mineral is found, in whisker-like form, in a gem-quality tanzanite host.

全5部の連載記事『カラー宝石（ダイヤモンド以外）の価値要因、デザイン、カットの品質』の第1部。この記事は、カラー宝石の価格に影響を与える主な価値要因について説明します。

Part 4 of 5 in the series "Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond)" digs deeper into cutters’ choices and explores additional factors used in the trade to assess relative value.

Part 5 of 5 in the series “Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond)” explores craftsmanship’s bearing on cut quality.