How to Evaluate Opals

Opals are beautiful, fiery gemstones that come in a wide variety of sizes, shapes and colors. Because the opal is an opaque stone that is very malleable and prone to scratching and other types of damage, you need to be very careful when purchasing opal jewelry. Also, because opals come in a vast array of selections and settings--and are sometimes even categorized by origin, as well as type of stone--you must be very sure that what you are buying is actually an opal and the type of gemstone you wanted.

Difficulty: Easy

Instructions

1. Decide how you plan to wear your opal jewelry. If you plan to wear your opal every day, you should select a bezel setting that will protect the stone. Opals are notorious for "wearing out" of their settings, as the stones are often soft and the prongs simply wear away at the stone over time. So if you decide on a pronged setting, you should make sure it comes with a warranty or periodic maintenance agreement in case of damage to the stone.

2. 
    
   A high "dome" on an opal tends to give the stone more flash and depth.

   Evaluate the shape of the stone. Generally, opals are cut in symmetrical, rounded shapes, and in the case of high-quality opals command a per-carat price similar to that of diamonds. If you are considering making a major investment in a piece of opal jewelry, make sure the stone has been cut and polished in such a way that the colors are shown to their best advantage. Naturally shaped opals also make striking pieces of jewelry, but they should not cost as much as a professionally shaped stone.

3. 
    
   Mexican opals can have red, orange, green, yellow and even blue "flashes" inside the stone, and are extremely valuable.

   Select a color. Opals showcase many colors, but most tend to have one dominant hue, such as milky white, black or even red. The more colors a stone has, the more valuable it will be.

4. Examine the opal for fire and rainbow brilliance. Opals can have inclusions and flaws just like diamonds, and these irregularities decrease the amount of fire that an opal displays. If there is a large cloudy or milky patch that does not emit any flashes of color even when the opal is moved around in good light, this is likely an inclusion and diminishes the value of the gem.

5. Although they are often somewhat opaque, opals can be rated on clarity, or the interior sparkle of the gem. Some opals are more crystalline than others, meaning that you can see some degree of light through them. They tend to be more valuable than fully opaque stones.

Tips & Warnings

• You should always retain the help of a trusted, licensed jeweler when you are considering a major jewelry purchase. Especially when the evaluation process includes so many custom considerations, experienced and objective advice will be invaluable to your ultimate decision.