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 ...

Figure 1. Pinctada maculata pearls alongside a Pinctada maculata mollusk valve with an attached blister pearl. The pearls range from 2.20 mm to 6.49 × 4.83 × 4.49 mm, and the shell measures ...

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 ...

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

Below is the list of recognized holidays when GIA locations will be closed.View the holiday schedule for all GIA locations worldwide.

Just over a century ago, in the summer of 1912, a workman’s pickaxe struck through the floor of an old tenement house in Cheapside, a commercial district near the renowned St. Paul’s Cathedral in ...

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 ...

Yogo Gulch, discovered more than 100 years ago, is one of four major sapphire-producing areas in Montana, United States. Yogo sapphires are known for their uniform, well-saturated blue color; relative ...

Figure 1. Six of the 13 cuprian liddicoatite tourmalines from this study. The faceted stones weigh 1.59–9.63 ct (average 3.95 ct). They are transparent and have greenish blue, green-blue, and green ...

Large quantities of rubies—both rough and faceted—from a commercially important new source in Myanmar (Burma) have been available on the Bangkok market since 1992. The ruby crystals from the Mong Hsu ...

Gemological, chemical, spectroscopic, and microscopic properties of blue-green color-change garnets from a new deposit near Bekily, Madagascar, are given. The samples are members of the ...

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