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Zircons
Specimen | Catalog Number | Locality | Weight |
---|---|---|---|
Zircon | NMNH G3568 | Thailand, Shantaboon | 105.90 ct |
Zircon | NMNH G3554 | Sri Lanka | 48.30 ct |
Zircon | NMNH G2237 | Sri Lanka | 97.60 ct |
Zircon | NMNH G2222 | Thailand | 103.20 ct |
Most gem zircons are found as waterworn pebbles in gravel deposits in Thailand, Cambodia, Vietnam, and Sri Lanka. Other localities include Burma, Madagascar, Brazil and Tanzania. Zircon is typically brown, reddish-brown, green or yellow. Since the 1920s virtually all zircon gemstones used in jewelry have been heat-treated to enhance their colors, producing blue, golden, and some colorless stones. Colorless zircon outperforms any other mineral imitating diamond as its dispersion and brilliance is almost as good as that of diamond. However, its inferior hardness and brittleness reveal zircon as an imposter. Like diamonds, zircons are typically cut as round brilliants to best show their dispersion or fire. The most popular zircons are the blue, colorless, and golden gems produced by heating.