Thank you to our member blogger today, Mary of Sandcastle Jewels:
My post last month focused on the differences between Natural Gemstones and Lab Created, with some added info on Synthetics. This month I’ll go over three industry standard treatments you’ll encounter when you buy Natural Gemstones…
The stones on the left in the photo are untreated Golden Rutilated Quartz, Chrome Diopside, Peridot, Iolite, Untreated Bi-Color Citrine, Untreated Amethyst, Welo Ethiopian Opal, Kyanite & Rhodolite Garnet. On the right, the treated stones are an oiled Columbian Emerald, Irradiated London Blue Topaz, Heated Tanzanite, Irradiated Morganite, Heated Burma Ruby & Fissure Filled Madagascar Ruby.**
It’s easy to think that, in a perfect world we’d all buy 100% untreated natural gemstones. But the truth is, without treatments, many of our favorite gems would be unattainable to all but the wealthiest among us. For you gem purists, there’s good news. A number of gemstones are almost always left untreated – Garnets, Peridot, Iolite, Spinel, Sunstone, Ametrine, Chrome Diopside, Rutilated Quartz and the majority of Labradorite. When you buy these gems, you’re usually safe to assume they are untreated
1) Hot Hot Hot…The most common treatment for 100s of years has been heat. Natural gems that were mined near areas of thermal venting in the Earth’s crust showed better, or different color, so heating became an acceptable way to offer improved, standardized colored gems. Most Citrine is actually heat treated pale Amethyst. Only a tiny fraction of Tanzanite actually comes out of the ground purple. Amethysts, Aquamarine, Citrine, Rubies, Sapphires, Tanzanite and Zircon are typically heat treated. However, Amethyst is still available and pretty affordable in its untreated state. But unless it’s specifically offered as Untreated, you must assume it’s been heated.
2) The Nuclear Option…The next common treatment is irradiation. During formation in Earth’s crust some gems are exposed to natural radiation. So gemologists found ways to mimic and speed up the process, which makes stones that would otherwise be ultra rare, attainable. No, your gems are not radioactive. But the Nuclear Regulatory Commission does regulate initial distribution of irradiated gems in the U.S. There is a required “cooling off” period after treatment. They must be held before they can be sold to assure their safety. Many times, irradiation (which alters the arrangement of the molecules) is followed with heat to achieve desired end color. Most colored diamonds today are irradiated. Morganite is irradiated. As is Kunzite. Some colors of Tourmaline are irradiated. And nearly all Blue Topaz, from Sky, to Swiss to London Blue, is irradiated White (colorless) Topaz.
3) Pretty Slick…Oiling is just what it sounds like. This treatment is used almost universally on Emeralds. As the rough is mined, it is placed in colorless oil. After cutting, the stones are re-oiled to assure that all the tiny fissures in the stone are filled. This is why you never want to have your Emerald jewelry steam cleaned. The steam can release the trapped oil and weaken the stone, leaving your Emerald looking a little shabby. A jeweler can usually re-oil your Emerald, but it’s better to be gentle when cleaning any gemstone, particularly Emeralds.
Next time I’ll talk more about treatments of Sapphire, Ruby, Opals & all things Mystic…