Gemstone | Treatment | Frequency | Remarks | ||
Diamond | Laser Drilled | Sometimes | Diamonds are laser drilled to bleach out dark inclusions. | ||
Diamond | Clarity Enhanced | Sometimes | Inclusions breaking the surface of the gemstone can be masked by placing a glass like substance in the crack. The substance tends to mask the location of the crack. | ||
Emerald | Oiling | Usually | When observing an emerald it is best to assume the gemstone has been oiled. | ||
Emerald | Epoxy like filler | Often | Many emeralds are treated with an epoxy like filler. The filler flows into the cracks on the surface of the gemstone. The filler tends to mask or hide the location of these cracks. | ||
Sapphire | heated | Usually | Most sapphires are heated to improve the color of the gemstone or the uniform distribution of color within the gemstone. | ||
Ruby | Heated | Usually | Heated to improve color | ||
Ruby | Dyed | Rarely | Dyed with colored oil to improve appearance | ||
Ruby | Heated to seal fractures | Often | Rubies are heated in a controlled environment in a borax solution. The borax can heal fractures in the surface of the stone. Occasionally the borax residue can be seen under 10 power magnification. | ||
Ruby | Clarity Enhanced | Occasionally | Rubies are occasionally Intentionally treated with a substance that fills surface cavities and fractures with a foreign material. This filler can have glass like properties | ||
Amethyst | Heated | Occasionally | Amethyst is sometimes heated to lighten the color or remove a brownish component | ||
Citrine | Heated | Usually | Amethyst is often heated to lighten the color to a yellow or yellow brown | ||
Tanzanite | Heated | Always | Zoisite (Tanzanite) is typically a yellowish brown color when mined. The gemstone is heated to produce the bluish purple to purplish blue color the public prizes | ||
Blue Topaz | Irradiated | Always | The gemstone is bombarded by neutrons to produce the blue color. | ||
Pearls | Bleached | Usually | Cultured Pearls are usually bleached to improve color. | ||
Pearls | Dyed | Occasionally | Black or gray pearls are typically dyed to these shades. Rose or blue tints are sometimes the product of dying. Freshwater pearls in a variety of colors are usually dyed. | ||
Pearls | Irradiated | Occasionally | Pearls are occasionally irradiated to produce black or gray colors. | ||
More to follow at a later date.. | If you have a particular question about a gemstone |