Hobbies And Interests
Heating
Heat treatment is the most common form of gemstone enhancement. Techniques can vary, from putting stones into a fire and "cooking" them, to using gas or electric furnaces at certain pressures to receive the desired effect. Heating is a permanent technique, used to enhance, intensify or a change a gemstone's color. Examples of heat-treated gemstones include carnelian, aquamarine, sapphire, citrine, ruby, amethyst and tourmaline.
Irradiation
Irradiation of gemstones to change or increase their color can occur naturally within the earth, but may take millions of years. Artificial irradiation only takes a few hours. Irradiation uses gamma rays, neutrons or high energy electrons to change a gemstone's color. This process is often followed by a heat treatment. Topaz, which in it's natural form, is a very pale blue to clear color, is irradiated to bring about its deeper shades of blue and even green. Other examples include tourmaline, ruby, chrysoberyl, cat's eye, kunzite and even cultured pearls.
Oiling
Emeralds are commonly "oiled" whereby oil, resin or wax is used to fill fissures in the gemstone's surface, thus making the stone's color more uniform. Other gemstones that may be oiled are opals (though rarely) and peridot.
Dyeing
Intensifying a gemstone's present color or improving its uniformity is sometimes brought about by dyeing, where color is added to the gemstone. Black onyx is always dyed to keep its rich, black color. Other gemstones that may be dyed are rose quartz, amber, carnelian, agate, lapis lazuli, jade, serpentine and turquoise.
Chemical Diffusion
The use of high heat temperatures with chemical additives to a stone's surface is chemical diffusion. The process leads to a more intense color or a complete color change altogether. Because chemical diffusion often results in artificially altering a gemstone's color, it must be disclosed on documents and advertising of the gemstone on which it is used. Rubies, sapphires and green topaz are sometimes chemically diffused.