This chart focuses primarily on the types of natural inclusions found in tourmaline, as well as the minerals in which tourmaline can be found as an inclusion. Treatments such as enhancement of ...

Jadeite is 6.5 to 7, and nephrite is 6 to 6.5 on the Mohs hardness scale. Hardness and toughness Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or ...

Lapis lazuli is an aggregate of several minerals. Lazurite grains provide its characteristic blue color, while golden flakes of pyrite can add attractive contrast. Lapis lazuli is a rock, which means ...

The GIA Gem Trade Laboratory (GTL) collected gemological data on 1,490 natural-color pink gem diamonds—both types I and II. While there was some overlap in gemological properties between the two ...

Figure 1. The color zoning of amethyst from Boudi often displays a characteristic hourglass shape. Photo by Abdelghani El Harfi and Salahaddine Mouaddib. For 25 years, the Moroccan locality of Boudi ...

A new diamond imitation, synthetic moissanite (silicon carbide), is now being produced by C3 Inc. in near-colorless form for jewelry purposes. With refractive indices of 2.648 and 2.691, a dispersion ...

Natural pearls grow in the wild without human intervention. They are very rare, and most natural pearls in the market today are antique. Cultured pearls are grown in pearl farms, and are the direct ...

Consumers now, more than ever, have a heightened awareness of sustainably and ethically sourced products. The GIA Diamond Origin Report uses scientific evaluation to provide confirmation of a ...

Treated cultured pearls with a “chocolate” coloration have entered the market from several sources. Gemological, spectroscopic, and chemical analyses were performed on both untreated and treated ...

Malaya garnets from Bekily, Madagascar, are predominantly pink to pinkish orange, with some stones orange to red. Discovered only in the late 1990s, the majority are intermediate members of the pyrope ...