The brilliant color variations and iridescence unique to opals make these lovely stones some of the most fascinating gems to own. There are, however, many different varieties and quality factors to consider when shopping for opals.
Opal Value Factors
Opals are classified and priced according to the overall body color, the unique play of color and the transparency displayed by each gem.
Body color refers to the underlying or overall color of the opal.
Colors range from colorless to milky white, gray and semi-black to black, and a wealth of vivid colors including red, orange, yellow and blue.
The depth and richness of color is reflected in pricing.
Play of Color
A phenomenon unique to opals, consisting of multiple color flashes within the stone that change depending on the angle from which the stone is viewed.
The density, intensity and distribution of these color flashes are determining value factors.
Opals are considered transparent when another object placed on the opposite side can be viewed through the stone; translucent, defined as having the ability to allow diffused light to pass through the entire gem; or opaque, meaning light does not penetrate the stone.
Transparency is of higher value than opaqueness.
Types of Opal
Also termed potch opals, this is usually an opaque opal exhibiting a milky but lustrous solid body color without any play of color.
Flashes of bright iridescent color or play of color is clearly evident within the opal.
Precious opals usually have a white or cream body color.
Transparent to translucent opals with a deeply saturated body color ranging from red to orange to bright yellow.
Fire opals do not usually exhibit play of color, but if they do, they are referred to as precious fire opals.
What Are Doublets and Triplets?
Opal forms in cracks and fissures deep in the earth.
Most often found in thin layers or plates, opal is sometimes left attached to the harder mother rock or, more frequently, bonded to a supporting layer of stronger material such as obsidian or glass.
The result of this process is known as a doublet. Doublets enhance the play of light an opal has to offer while adding durability.
A triplet is constructed of a bottom layer of material, a layer of opal, and a smooth top covering such as plastic, crystal or glass for protection.
Since opal is a very soft stone, easily scratched or fractured, doublets and triplets are common jewelry applications.
When shopping, first determine the type of opal you are looking at, then consider the value factors.
Ascertain the quality of iridescence; the play of light should be visible from all angles with strong color patterns representing a range of color.
Consider the body color. Dark overall color is rarer and thus commands higher pricing.
Take transparency into account. Generally speaking, greater transparency equals higher value.
Examine the opal for doublets and triplets, which make the stone far lower in terms of value than solid opals.
Popular Gem-Quality Opals
• White Opal: The most common precious opal found on the jewelry market. It exhibits play of color on white or light body color. Pricing is determined by intensity of iridescence.
• Black Opal: An opal commanding high prices with body color ranging from gray, black and blue to green. This dark background makes the fiery play of color more visible.
• Lightning Ridge Opal: High quality black opal, mined in Lightning Ridge, Australia, the “Black Opal Capital of the World.”
• Crystal Opal: A transparent or translucent opal that exhibits play of color.
• Harlequin Opal: An opal with vivid patches of iridescence in the shape of diamonds or rectangles; one of the rarest and most prized variations.
• Pinfire Opal: An opal containing many pinpoints of iridescence throughout the stone.
• Cat’s Eye Opal: A very rare opal containing a thin line of iridescence that is visible from multiple directions and capable of tracking across the stone.
• Mexican Fire Opal: A bright orange to red transparent opal mined in Mexico, the largest supplier of fire opals.
• Jelly Opal: Also called water opal, this is a colorless, transparent common opal with a gel-like appearance. This term also refers to a transparent precious opal having a gel-like appearance with a bluish sheen.
Where to Buy Opal Jewelry?
Take a look at the great selection of opal pieces available at Amazon.