Heated Blue Sapphire

Sapphire is one of the most popular of all colored gemstones. Like all precious gems, they are rare and expensive. You can find natural sapphires offered for sale at prices exceeding several thousand dollars per carat. Very fine specimens can run considerably more.

But you will also sometimes see sapphires offered at much lower prices, sometimes for as little as $30 or $50 a carat. What is the reason for this vast range in price?

Sapphire Cabochon

When you see sapphires for sale, the first thing to look for is whether they are natural or synthetic. Though synthetic sapphires are chemically the same as natural sapphire -- they are both corundum or aluminum oxide -- synthetic sapphire is mass produced in laboratories at low cost using a method known as flame fusion. Generally, reputable gem dealers will not sell synthetic sapphire. It is used mainly in low cost commercial jewelry. It should always be disclosed as synthetic.

Beryllium Treated Sapphire

When you encounter low cost natural sapphire in the market it is mostly treated or lower quality material. Lower grade material is typically of poor color or clarity. Some of the lower grade material of poor transparency is cut as cabochons rather than faceted. If the color is good, these can be very attractive, but they will sell for much lower prices than facet-grade stones.

Sapphires of inferior color can sometimes be improved by treating the stone with various methods. A relatively new method that is used on off-color stones is known as beryllium heat treatment or lattice diffusion. It involves heating sapphire with the light element beryllium, which dramatically changes the color of the gem. Most beryllium-treated sapphire is a vivid yellow, orange or orange-red. As this treatment becomes more common and accepted in the trade, prices on these diffused stones are rising.

4 Carat Unheated Blue Sapphire

The most common treatment method for sapphire is heat treatment, which involves high-temperature heating that affects impurities in the sapphire, such as titanium or iron. The end result is often an improvement in both the color and clarity of the gem. Heat-treated sapphires with top color and clarity can be quite expensive, especially in larger sizes.

The rarest and most expensive sapphires are completely untreated. Sometimes they may be found at affordable prices in smaller sizes (under 1 carat), but unheated sapphires over 1 carat will generally be expensive. Large stones (over 2 carats) with very good color can easily sell for $1000 a carat and often more.

First Published: December-25-2009

© 2005-2013 GemSelect.com all rights reserved.
Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.