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Ed Bristol

Gemstone treatments

New challenges for the gem trade.

Today most gemstones have been heated, radiated, diffused, filled, dyed, bleached, oiled, or any possible combination of these.
(Photo: High-tech gemstone burner)

Low-grade sapphire is radiated and burned into blue or diffused into orange, white topaz is radiated into London blue, brown zircon is cooked blue, quartz becomes citrine, and so on.

New technologies create gems that are essentially man-made but are sold as "natural".

(Photo: unknown filling in Burma ruby)

Some treatments are known and legal, others are considered cheating, some are permanent, and others fade. Some traders disclose treatments, some don't.

What really happens to gemstones is hidden in Asia. Even the best gemologists can hardly oversee every new process that is used to "enhance" a gemstone.

New treatments are developed in more and more rapid succession. Every new treatment needs months, or even years, to be indentified. Meanwhile the door is wide open for fraud and misuse.

Here are the latest treatments and new fakes:

  • Andesine, sold for years as an expensive natural red gem and adopted as the Olympic gemstone, has turned out to be in fact cheap brown-yellow African labradorite, secretly heated and diffused with copper and iron. Buyers are now suing Jewelry Television (JTV) for fraud.
  • GAAJ and GIA have found synthetic rubies in the market which were heated in order to disguise their artificial origin. They are offered as "Natural Heated Ruby". The normal gem testing process in a laboratory will easily fail to identify a heated ruby as synthetic.
  • GEMLAB from Germany has warned of a new type of synthetic quartz which is heated and then passed off as natural ametrine. Ametrine is always heated. Basically this new trick goes a long the lines of heating synthetic ruby to sell it as "heated natural".
  • Cobalt coated tanzanite was found by the GIA. Tanzanite is always heated into permanent color change but this "color" can be scratched off.
  • The GAAJ has identified rutilated quartz filled with oil and resin in order to improve clarity.
  • The process of lead-glass filling for star rubies in Thailand has been described by Vincent Pardieu. Lead glass filled rubies have been around for some years but the low-heat version (800-1200 degree C) for star rubies is new.
  • A new "center-fusion" to color topaz has been developed by Sithy Gems. So far Topaz was irradiated into blue, vapor-color coated  into "Mystic Topaz", and diffused into blue and green. The new center-fusion is basically high-pressure-heat gluing of an artificially colored piece of topaz onto a colorless topaz. From the companies' brochure:
    Top Colors of Expensive Gemstone which will resemble as High-Priced Gemstone once mounted in Jewelry. Only Gemologist could reveal the secret upon testing."
    (clear invitation to fraud?)
    The same company also offers color-coated Tsavorite and moonstones. Scary. 
  • Gem Research Swiss (GRS) has found bismuth-based glass filler in pink sapphires and rubies.
  • A new type of blue sapphire is produced by inducing cobalt oxide under high-heat into colorless or brown corundum. The new process is called "Tanusorn" and was developed in Thailand, reports the GAAJ. The resulting sapphires are not very nice but cheap and widely available. 
  • The GIA has found lead-glass filled color change sapphires. Lead-glass filling can essentially be applied on any fractured or fissured gemstone but was so far mostly used in ruby. This year lead-glass filling has started to show up in other varieties, too.

Too much to stomach? We think so too. 


Here are the main reasons why treated gemstones must be disclosed as such and have to be far cheaper than natural gems:

1. Heated gemstones are less durable.


Extreme heat causes a gem's surface to become brittle. Over time the faceted edges of a heated gemstone will wear out and the stone will begin to look dull or chip, reducing his future value even more.

(Photo: "chipped" heated sapphire)

2. Treated stones might be a risk to health.

Ever since gems exhibiting radioactivity or containing beryllium have appeared on the market people worry about what else might have been done to the gemstones they wear.
(Photo: radiated tourmaline)

3. Treated gemstones are unnatural and not rare.

Before and after radiation: Topaz

Geuda - 18 tons are
exported per annum

Sapphire in most unnatural
color made from Geuda

More and more people think that turning an ugly pebble into sapphire is not "enhancing" of natural beauty, but fake.

Ted Themalis (the grandmaster of gemstone treatment):

"For years I have been saying that the definition of "gem" must be changed: A gem must be untreated to be called GEM!"

4. Treated stones do not retain value.

A gem's value is determined by its rarity. The past has shown how entire varieties were devaluated when new treatments hit the market:

  • Prices of heated yellow sapphire crashed over night when newly treated yellows flooded the Tucson Gem Show in the 90s
  • Blue topaz is now sold for a few dollars since it became possible to radiate and heat colorless stones into sky blue ones
  • Thousands of BE treated padparadschas appeared recently in Japan and prices for treated pink-orange sapphires have dropped by 80%.

The gem trade is thrown into turmoil, but the public demand for product information is simply normal: 

"Educated consumers do not [anymore] appreciate buying products of questionable origin containing unknown ingredients induced in secret production from countries notorious for bad consumer protection."

On their ways from the mines to Japan, America or Europe most gems pass through so many different hands and countries that no one really knows what has happened to them and where they came from.

The traditional supply chain is a mess when it comes to transparency and product information. Therefore Wild Fish has implemented its own sourcing methods and offers only certified and untreated gemstones. 

Edward Bristol


Natural Gemstones Only!

No Heat, No Radiation.
No Bleaching, No Oil.
No Filler, No Diffusion.
No BE, No Chemicals.

Nothing but... gems!

Made by Earth.


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