How to Buy Opals

The birthstone of October, opals are a fascinating stone. The fire in the opal, caused by diffraction, displays all the colors of the rainbow. Almost 95 percent of opals are found in Australia, although they have also been located in the Czech Republic, the U. S. and Central America. Opals contain water; the quantity of the water makes the opal unique. To buy opals, use these steps.

Instructions

1. Determine solidity. Many lower priced opals are actually doublets or triplets. Doublets are thin shavings of opal glued onto another, cheaper substance. The glue is sometimes dark colored to mimic a black opal. Triplets are doublets with an additional clear top layer, sometimes of quartz, used to protect the thin opal layer. These opal "sandwiches" are less desirable and valuable. Look at the side of the opal to find evidence of a layer.

2. Look for play-of-color patterns. The beauty of an opal is in its play-of-color, those flashes of color that come out of the opal. The best opals have many different colors, in large flashes, widely dispersed across the stone. Beware of regular grid patterns in the opal's fire. This may indicate a man-made synthetic opal.

3. Examine the background color. Black opals, which are actually any dark color, such as dark green, dark brown or black, are the most prized. Dark gray, followed by light colored opals are next on the value scale. Transparent or nearly transparent are the less desirable colors for an opal, as they do not show the play of color, or fire.

4. Evaluate the color display. The more colors the opal shows, the more valuable it is. Reds, violets, yellow and oranges are good colors for the display. Less valuable are blue and green; gray play-of-color is not desirable.

5. Check the size. Opals are sold by carat weight; the larger the carat, usually the more expensive. However, the variations of opal colors, both in body color and display color, make a big difference in price. Opal doublets and triplets should be sold only by the stone, not weight.

Tips & Warnings

• Always compare opal prices from several sources. An opal that is priced too low in comparison to similar stones should be suspect. Deal with a reputable jeweler when purchasing opals.

• Opals are soft by nature. Take care when wearing an opal so that it does not crack.