Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with which one mineral can be scratched by another. But the Mohs scale is deceptive.

GIA uses a comprehensive standard it developed over a 70-year period of ground-breaking research on pearls, called The GIA 7 Pearl Value Factors ™ (Size, Shape, Color, Luster, Surface, Nacre, and ...

Search GIA's library catalog of 65,000 books, 230,000 images, 2200 videos, 1200 periodicals, and the renowned Cartier Rare Book Repository and Archive.

With a reach that spans the globe, GIA is a nonprofit institute dedicated to protecting consumers by ensuring their trust in gems and jewelry through cutting edge gemological research, rigorous ...

The history and geology of the Swat deposit were comprehensively reported by Arif et al. (2011) and Giuliani et al. (2019) and are summarized here. However, a detailed study of the inclusions and ...

Christopher M. Breeding, Sally Eaton-Magaña, and James E. Shigley ...

Part 2 of 5 in the series: Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond). This article establishes a common language for discussing cutting styles, with a focus on basic ...

Figure 7. This is a replica of a Qing dynasty hairpin recovered from a tomb in Beijing. The two main pearl-mounted patterns, composed of two layers of gold threads, are called ruyi in Chinese and ...

Figure 4. Randomly selected samples under daylight-equivalent light (left) and under long-wave UV light (right). Copper-bearing liddicoatite (CT05, CT03, and CT06 at the top) show stronger ...

More ephemeral than the diamond ring, the rush ring was hastily made from leaves or grass and lasted in many cases as long as the short-lived engagement. A more enduring and popular 16th century ring, ...

Yusuke Katsurada, Ziyin Sun, Christopher M. Breeding, and Barbara L. Dutrow ...

The Montepuez ruby deposit was discovered in May 2009 (Pardieu et al., 2009). Shortly thereafter, thousands of miners, supported by foreign traders, began to illegally work the area. This continued ...