Enhancements in Gemstones

Enhancements in Gemstones

Posted by BarlowsGems on 19th May 2023

First off you may ask what is a gemstone enhancement?

An gemstone enhancement is any process, other than cutting and polishing, that improves the appearance (color or clarity), durability, or availability of a gemstone.

In 1957, the Federal Trade Commission, with the co-operation of the Jewelers Vigilance Committee, advised the jewelry industry to inform consumers of gemstone enhancements. This is a list of types of enhancements and a list of which gemstone materials these enhancements are commonly used on. We do not claim that all of a certain material is enhanced, but we will use terms like usually, occasionally, and rarely to describe how common the practice is. Some enhancements are easily to detect or can be detected by an experienced gemologist. Other enhancements are almost impossible to detect. We recommend that the jeweler or consumer always assume that a listed stone is in fact enhanced when wearing or cleaning the stone to avoid damage to the stone.

Reputable jewelers will always disclose these enhancements when selling the stones.


  • Bleaching- the use of bleach or other chemicals to lighten or remove a gemstone’s color. All types of pearls are routinely bleached with hydrogen peroxide to lighten and improve their uniformity of color. White coral, ivory and bone are commonly bleached to maker it whiter. Jadeite is also commonly bleached.
  • Coating- Using lacquer, enameling, inking, foiling, or covering with metal oxide or other substance, to provide color or add special effects to the gemstone. Sometimes gemstones are actually painted on the back to add color. This technique is rarely used on diamonds, tanzanite, topaz, opals and pearls. And commonly used on quartz, but usually obvious because of the odd colors or effects.
  • Dyeing- Dyeing or coloring a gemstone to change, intensify, or improve the color or color uniformity. The process has been used since ancient times for materials such as coral, turquoise, lapis lazuli, jade, chalcedony, quartz, sodalite and serpentine. Howlite is commonly dyed to look like turquoise. Emeralds, ivory and bone, and low-quality pearls are occasionally dyed. It is rarely done to opals, rubies and black pearls. The picture for this blog is of a Tuxedo Agate. Tuxedo Agates are Brazilian Agates that are an uninteresting gray and white color. These are dyed black, which for some reason is only absorbed by the gray parts, making a very attractive black and white stone.
  • Filling- The concealing of surface cavities, cracks, or fractures usually with colorless wax, oils, glass, resin, or plastic, or other foreign substance. This type of enhancement is not very prevalent but has been used on diamonds, emeralds, rubies, quartz, aquamarine and other transparent gemstones.
  • Heating- The use of high heat to alter the color or clarity of a stone. Citrine and Zircon is almost always heated. Citrine is usually made by heating Amethyst. Ruby, tanzanite, topaz and sapphire are commonly heated. Amber, pink beryl, aquamarine and tourmaline are occasionally heated. Amethyst is rarely heated.
  • Impregnation (or Stabilizing)- General infusion of a substance such as paraffin, plastic, polymer or wax into a porous gemstone material to give it more stability. The most commonly encountered wax or plastic impregnated gemstones are opaque, and they include turquoise, chrysocolla-malachite, lapis lazuli, jadeite, nephrite, amazonite, rhodochrosite and serpentine.
  • Irradiation- The use of a high energy or subatomic particle bombardment exposure (artificial source of radiation) to a gemstone to change or improve its color. Gemstones that are commonly irradiated include blue or yellow beryl, colored diamonds, topaz (blue is usually done), tourmaline, and quartz.
  • Lasering- The use of a laser and chemicals to reach and alter deep inclusions or flaws in diamonds.


If a stone is dyed or coated you should avoid repolishing it and, in some cases, chemicals, ultrasonic cleaning and prolonged exposure to sunlight.

If a stone is heated you should avoid chemicals and ultrasonic cleaning.

If a stone is impregnated or filled you should avoid hot water, heat, chemicals and ultrasonic cleaning. Special care must be taken not to subject gemstones with wax or plastic impregnations to heat, such as that encountered by a jeweler’s torch, since these will likely damage the material.

If a stone is oiled you should avoid temperature changes, chemicals and ultrasonic cleaning.

If a stone is irradiated there are usually no special care requirements. However, in beryl and kunzite, the irradiated color tends to be short lived and fades upon exposure to bright light.

For all pearls, opals, coral, ivory or bone you should avoid chemicals, abrasives, and cosmetics. Also avoid heat on opals.

Even if not treated copper gems such as Chrysocolla, Malachite, and Azurite and many other softer semiprecious stones should not be exposed to heat, chemicals or ultrasonic cleaning.

Here at BarlowsGems we specialize in natural semiprecious stone cabochons.  We will always disclose any enhancements.

Thanks for reading!