With proper care, citrine is a beautiful and versatile gemstone for jewelry use. – Robert Weldon Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or ...

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 ...

A peridot-like bright greenish yellow to green gem material called “green amber” has recently appeared in the gem market.

Figure 1. Left: The Blue Moon diamond as the 29.62 ct rough discovered in January 2014 at the Cullinan mine in South Africa. Right: The faceted Blue Moon diamond, a 12.03 ct cushion modified brilliant ...

Despite the commercial value of natural-color diamonds, distinguishing them from treated diamonds remains a significant identification challenge. While some diagnostic visual features exist ...

Scientific advances in the past decade have completely altered our understanding of certain concepts relating to the age and origin of diamonds. As a generalization, most diamonds formed more than 990 ...

Figure 1. The GIA 7 Pearl Value Factors system classifies pearls according to size, shape, color, luster, surface, nacre, and matching. Composite photo by GIA staff. Prized by many cultures throughout ...

Fancy color diamonds are among the rarest and most valuable gemstones. Diamonds in the normal color range are colorless through light yellow and are described using the industry’s D-to-Z color-grading ...

One of the greatest concerns with emerald filling is the degree of clarity enhancement such treatment represents. Stones that appear to have excellent clarity with the unaided eye are often revealed ...

The successful culturing of abalone pearls has been known since French scientist Louis Boutan’s experimentation in the late 1890s, but commercial production has been achieved only in recent decades.

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 ...

The Santa Terezinha de Goias emerald deposit, currently the most important source of emeralds in Brazil, lies northwest of Brasilia, in the State of Goias. The emeralds, most of which are stones of a ...