Wednesday, September 23, 2009

Gemstone Treatments

The topic of gemstone treatments can be confusing for someone shopping for a gemstone. Many people are surprised to learn that most finished gems being sold today have been treated in some way. But that it isn't necessarily a bad thing. The most common treatments are heating, irradiating, dyeing and diffusion. Many types of treatments are considered acceptable in the jewelry trade while others are not. The important thing is that the treatments are disclosed so that you can make an informed buying decision.

The purpose of a treatment is generally to make a gem more beautiful than it would be without the treatment. Some treatments may make a stone more durable. In most cases the treatment is acceptable if it is permanent, improves the qualities of the gem, is disclosed and is not meant to mislead the buyer.

A few types of gems including garnet, peridot and iolite are not usually treated, but most other familiar gemstones usually are. For instance, most all sapphires are heat treated to improve their color and clarity. Heated sapphires display brighter, more even color that would be extremely rare in a natural stone. Therefore most commercially available sapphires have been heated. That usually means you can a afford a more beautiful stone than you could if sapphires were not heated. Heat treatment is widely accepted in the trade. Most of the amethyst now being sold has also been heat treated to improve the color and make it more even.

Some sapphires receive diffusion treatment to alter their color. Through heat and pressure, a particular chemical element is diffused into the cut stone, thereby changing the color. That' the case with many- of the “padparadscha” (pinkish-orange) sapphire that is on the market. However diffusion only effects a thin outer layer of the stone, so if the stone is scratched a little or chipped the original color will show. For that reason, this is often considered an “unacceptable” treatment unless the buyer is fully aware of the treatment and its risks.

Many people like the idea of having an untreated stone. They feel that part of the attraction of gems is that it is something created by nature, without any human manipulation. They prefer untreated stones even if it is more expensive or they have to sacrifice color or clarity a little. Treatment is so commonplace that untreated gemstones are becoming rare and so, they may have more value to a collector or purest.

Below is a list of some of the treatments that are usually deemed “acceptable” by the jewelry trade:

  • heating sapphires and rubies
  • heating aquamarine, amethyst, citrine, tanzanite, topaz, tourmaline, and zircon
  • irradiating topaz (to make clear topaz blue)
  • putting organic resins and wax in emeralds
  • waxing lapis lazuli, jade, and other opaque gemstones
  • dying onyx black

Many of these treatments are virtually undetectable, so whether or not they are treated is difficult to prove. Many stones are sold as “probably treated” and you should assume the stones you are buying are, unless it is specified as “untreated”. You may see the term “natural used”. The term “natural gem” means that the stone was formed in the earth. In other words, it is not synthetic, man-made or lab created. But it may be treated and can still be called natural!

Here are some of the treatments that are usually considered “not acceptable”:

  • diffusion treatment of sapphire
  • glass filling of ruby
  • epoxy resin in emerald
  • dyeing lapis lazuli blue, or most other dye treatments
  • epoxy treatment of jadeite

Even these treatments are not illegal or even unethical as long as they are fully disclosed. Ultimately, it is a personal decision whether you buy a treated, untreated or synthetic gemstone. The important thing is that you know what you are buying.

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