Since ancient times, gemstones have been treated in a variety of ways to increase their beauty. An example is the bleaching of bone or ivory to improve the color. There exist many techniques to enhance the appearance of gemstones and in fact nearly all gemstones on the market today have been treated in some way, as they have in the past. In addition, new techniques have been developed in recent years (for example, laser treatment and irradiation) and new ones are being developed all the time. This only becomes a problem if consumers are led to believe that their gemstones have not been treated, and are worth more than they really are for this reason. A partial list of the common treatments of gemstones is given below.


Agate Dyed
Aquamarine Heated to improve color
Black Onyx Dyed
Carnelian Agate Dyed
Citrine Heated to produce color
Coral, White Bleached white coral
Coral, "Gold" Bleached black coral
Diamond, colorless Laser drilled and/or filled to improve appearance
Emerald Oiled with colorless oil to improve appearance
Ivory & Bone Bleached to whiten
Jadeite Impregnated with wax
Lapis Lazuli Dyed; Impregnated with wax or oil
Pearl, natural Bleached to improve color and appearance
Pearl, cultured Bleached to whiten, dyed for colors
Ruby Heated to improve color
Sapphire Heated to optimize color
Serpentine Dyed
Sodalite Dyed
Tanzanite Heated to produce color
Topaz, Blue Irradiated or heated to produce color
Topaz (Yellow/Orange) Irradiated to intensify color
Topaz, Pink Heated to produce color
Tourmaline (Green/Blue) Heated to improve color
Turquoise Impregnated with oil or wax to enhance color
Turquoise Stabilized with plastic to improve color & durability
Zircon (Blue, Red & Colorless)  Heated to produce color