AZGem Gems
May, 2001
The World's Most Useful
Gem & Jewelry Monthly Newsletter

Written by Carolyn Doyle for customers of
The Dorado Company
and other visitors to the website who subscribe.


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Usable Gems... and a little opinion.

Gem Enhancement

Gem enhancement is a poorly understood subject, even within the jewelry trade.

Thankfully, most gem stone dealers have at least a working knowledge of the subject.

So, I thought it would be helpful to discuss gem enhancement this month.

What Is Gem Enhancement?

Gem enhancement is man applying a treatment process to a natural gemstone. Miners and cutters usually perform gem enhancement.

Enhancement is performed to improve the appearance and value of a gem, and is intended to benefit consumers as well as the miner or cutter.

If enhancement didn't exist few beautiful gems would exist... and they would be so expensive that only the very rich could afford them. Supply and demand, you know.

For the miner or cutter there is no reason to spend the time and money to enhance a gem if it doesn't add value.

As you've guessed by now, I'm not opposed to enhancement… as long as the enhancement is long lasting.

Enhancement Methods

The most common and long lasting enhancements mimic nature.

Nature applies heat, pressure, radiation, and even bleaching to some gems.

Heat treatment usually produces a permanent change in a gem's color.

Applying heat to gems susceptible to heat treatment can lighten or darken the gem's appearance. A good example of this is aquamarine. Applying heat often darkens the blue color, and sometimes drives off any green undertone.

Heat can also reduce the appearance of inclusions. Ruby and sapphire can be made more transparent by disbursing "silk" within the stone.

Heat can even entirely change a gem's color. For example, applying heat to brown zoisite produces tanzanite. The chance of finding an unheated tanzanite gem is probably less than 1 in ten million.

High heat and pressure in the presence of a coloring agent produces an enhancement called diffusion.

Sapphire, ruby, and topaz are good subjects for this method of enhancement.

Near colorless sapphire when super-heated in the presence of alumina, iron, and titanium produces blue sapphire.

Some gems are irradiated… either naturally or deliberately by man. Yellow sapphire, blue topaz and some pearls are examples of gems that owe their color to low level exposure to radiation.

In the U.S., the Nuclear Regulatory Commission regulates the treatment or importation of these gems to ensure safety.

Pearls are commonly bleached (and sometimes dyed) to enhance their appearance.

Emeralds often have an oil applied to deepen their color and fill tiny surface voids.

There are many other methods of gem enhancement, but the ones discussed here are the most common for faceted colored gems.

Gem enhancement has been practiced for 5ooo years that we know of. I believe it's here to stay.


Disclosure of gem enhancement is a matter of ethics and law.

The U.S. Federal Trade Commission has rules requiring disclosure of gem enhancement at every level.

Reputable gem dealers and jewelers have routinely disclosed enhancement of gems to their customers… even before the gem industry requested the FTC to put requirements in place.

Gem enhancement is very common. At The Dorado Company we find it more accurate to assume that all gems are enhanced… unless we know for a fact a particular gem is NOT enhanced.

On our web pages you will see the term "untreated" applied to certain gems we helped take from the earth. We're positive these gems aren't enhanced.

For example, our Four Peaks Amethyst is untreated. Our Ant Hill Garnet is also untreated.

We also apply this label to a few gems we buy from certain trusted fellow dealers who witnessed the stone being mined.

Some people prefer gems that aren't enhanced. Others don't care… they're primarily interested in the beauty of a particular gem stone.

Big Studs

If you haven't checked out the 7-mm stud earrings featured on our website, please use the link below to do it now.

The earrings are great, and so are the low prices!


Free Shipping

Don't forget, we're offering free shipping on all orders over $99.

Just deduct the shipping charge when you fill out the order form. If you forget, we'll deduct it for you.


Until next month… please, visit me anytime at for a great selection of colored gems at great prices.

Carolyn Doyle

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The Dorado Company
P.O. Box 8232
Scottsdale, AZ 85252-8232