With demand for top-color gemstones far exceeding nature's supply, jewelers have developed ways to enhance the appearance and durability of more common stones. Some of these treatments, or enhancements, are permanent; others are temporary. In many instances, the treatments mimic what happens to stones while being formed in the ground, and are therefore viewed as simply finishing what nature started.
Gemstone enhancement has become such a common, accepted practice that experts believe the vast majority of stones for sale in stores today are treated in some way. From a consumer's point of view, gemstone enhancements allow you to buy better-looking stones at a fraction of the cost of comparable untreated stones.
According to the Federal Trade Commission's Guides for the Jewelry Industry, jewelers must disclose to the consumer all gemstone treatments that are non-permanent or require special care. On the flip side, jewelers are not required to disclose permanent treatments that don't require special care.
Heating is one of the most common treatments used to enhance the natural beauty of colored gemstones. It is a permanent process the can dramatically improve the color and/or clarity in a number of stones, including sapphires, rubies, diamonds, aquamarine, amethyst, tanzanite, topaz, tourmaline and other stones.
Many stones also are treated with radiation, a permanent process that can enhance their color. Irradiation is commonly used on yellow beryl, smoky quartz, freshwater pearls, diamonds, and pink to red tourmaline. But perhaps the best-known irradiated stone of all is blue topaz - which is generally colorless in its untreated state.
Some stones have their surface color enhanced through the use of chemicals in conjunction with high temperatures in a process called diffusion. Rubies and sapphires often have their color improved through this treatment.
Fracture-filling is the process of filling surface cavities, fractures or other inclusions of a stone with a colorless hardening agent. The process can make such flaws less visible and make the stone more salable. This treatment is most associated with diamonds and emeralds. However, a wide range of stones are routinely injected with plastics, resins, glass, oils, waxes or other materials. Heat, ultrasonic cleaning and ultraviolet light may affect the durability of these fillings.
Laser drilling is the process of drilling holes into a stone with a laser to cut out inclusions. This permanent treatment is most commonly associated with diamonds and doesn't have to be disclosed, according to the FTC.
Oiling is one of the oldest methods of colored stone enhancement and is now used almost exclusively on emeralds. Emeralds are often oiled (and waxed) to enhance color, smooth out their finish and hide surface cracks that appear naturally in the stone. Although the oil may eventually dry out, it can last for years before needing replacement.
More porous materials like jade, pearls, amber, coral, ivory, lapis lazuli and other gems may be dyed to improve color uniformity. Pearls and ivory also may be bleached to lighten their color.
It's important to remember that most gemstone enhancements greatly improve the appearance - and hence the value - of a stone. But as always, if you have any questions about stone enhancements, consult your jeweler. Reputable jewelers fully disclose gem treatments at the point-of-sale and are more than willing to discuss them with customers.