Gemstone Enhancement
It may upset some purists to know that almost all the gemstones on the market, both loose and those set in jewellery, have been enhanced in some way. This is a common practice, however, and widely accepted by the industry. The American Gem Trade Association currently defines gemstone enhancement as 'any traditional enhancement process other than cutting and polishing that improves the appearance, durability or availability of a gemstone.' The most common methods are listed below.
Heating
Almost all the gemstones in the marketplace have been exposed to heat to improve their colour or clarity, often as a combined effect. Applying heat can modify the stone's chemical makeup, as well as causing its inclusions to dissolve or change, permanently enhancing not just its clarity but also its colour. The reason why the international jewellery industry widely accepts such a method is that gemstones located deep below the earth's surface are constantly exposed to heat and, therefore, this process may occur naturally.
Irradiation
Exposing a gemstone to radiation is another way of permanently intensifying its natural colour, and this method is often applied in combination with heat treatment. This process alters the dispersion of electrons within the gemstone and, in some cases, can turn a colourless gemstone into one that exhibits a bright rainbow of colours. While this enhancement method has been known to fade with time, reports of such incidents have been rare.
Dyeing
This is the process of brightening a gemstone's colour, or evening it out, through the application of permanent dye to the stone. The effect is almost always permanent, with only a few rare cases of the enhancement fading over time.
Bleaching
This is when a gemstone's colour is enhanced, lightened, or removed using elements such as light, heat and chemicals.
Filling, Impregnation or Oil/Resin Infusion
An ancient practice that has been refined and modernised over the years, this practice involves artificially filling in a gemstone's natural cavities with colourless glass, plastic, wax, oil or resin to improve both its weight and appearance.
Coating
Some gemstones are coated with lacquer, enamel, ink or films to enhance their appearance and/or strength.
Lasering
This technique uses laser technology to repair or remove a gemstone’s internal inclusions and/or external blemishes.
Common Enhancement Methods Applied To Gemstones
| Gemstone | Enhancement Method |
|---|---|
| Amythyst | Usually heated to improve color |
| Aquamarine | Usually heated to improve color and appearance |
| Black Onyx | Dyed |
| Blue Topaz | Usually heated/irradiated to enhance blue color |
| Citrine | Usually heated/irradiated to enhance color |
| Coral | Commonly bleached |
| Diamond | None |
| Emerald | Oiled with colorless oil |
| Garnet | None |
| Jade | Impregnated with colorless wax |
| Lapis Lazuli | Impregnated with colorless wax or oil |
| Opal | Coated to improve surface strength and appearance |
| Pearls | Commonly bleached, dyed, polished or coated to improve color and appearance |
| Peridot | None |
| Ruby | Usually heated/infused to enhance color and clarity |
| Sapphire | Usually heated/infused to enhance color and clarity |
| Tanzanite | Usually heated/infused to enhance color and clarity |
| Tourmaline | Commonly irradiated to intensify pink, red or purple color |
