Materials and Results
| Effects of irradiation on various gemstone materials |
||
|---|---|---|
| Material | Starting color | Ending color |
| Beryl | Colorless | Yellow |
| Blue | Green | |
| Colorless (Maxixe-type) |
Blue | |
| Diamond | Colorless or yellow to brown |
Green to blue |
| Fluorite | Colorless | Various |
| Pearl | Light colors | Gray to black or gray-blue |
| Quartz | Colorless to yellow or pale green |
Brown, amethyst, "smoky", rose |
| Topaz | Yellow to orange | Intensify colors |
| Colorless to pale blue | Brown, blue, green | |
| Tourmaline | Colorless to pale colors |
Yellow, brown, pink, red, green-red (bicolor) |
| Blue | Purple | |
| Zircon | Colorless | Brown to red |
| Source: Ashbuugh III 1988, p. 201 | ||
The most commonly irradiated gemstone is topaz, which becomes blue after the process. Blue topaz is very rare in nature and almost always the result of artificial irradiation. According to the American Gem Trade Association, approximately 30 million carats (6,000 kg (13,000 lb)) of topaz are irradiated every year globally, 40 percent of which were done in the United States as of 1988. As of 2011, no topaz is neutron irradiated in the US; major treatment areas are Germany and Poland. A lot of linear accelerated treatment is done in Bangkok.
Diamonds are usually irradiated to become yellow, blue-green or green, although other colors are possible.
Quartz may be irradiated to produce amethyst and other colors.
Colorless beryls, also called goshenite, become pure yellow when irradiated, which are called golden beryl or heliodor.
Pearls are irradiated to produce gray blue or gray-to-black colors. Methods of using a cobalt-60 gamma ray facility to darken white Akoya pearls were patented in the early 1960s. But the gamma ray treatment does not alter the color of the pearl's nacre, therefore is not effective if the pearl has a thick or non-transparent nacre. Most black pearls available in markets prior to the late 1970s had been either irradiated or dyed.
Read more about this topic: Gemstone Irradiation
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