Opal is a translucent form of silica that boasts an iridescent play of colors and which occurs in a wide rainbow of colors, including white and black. The deeply colored stones with an intense “fire” of many colors are the rarest and most valuable opals. Varieties of opal include milk; fire; black; Brazilian; yellow; and red; as well as opal triplet; opal doublet; and opal mosaic. Opal is the October birthstone and is the commemorative gemstone for the 14th wedding anniversary.
•Where is opal found?
The main sources for gem quality opal today are Australia and Mexico; and Oregon and Nevada (and elsewhere) in the United States. Opals are also mined in Czechoslovakia, South Africa, and Brazil (Brazilian opal).
•Color
Opals occur in a wide range of qualities and colors. Here is an overview of the different types of natural opals:
- Milk: Also known as “light opal”; “milk” opal refers to a group of opals with a white background and a play of colors ranging from almost none, to a brilliant play of colors. Included in this category are white opals, grey opals, crystal opals, and jelly opals.
- Fire: Fire opals occur with red, orange, or yellow body colors and can exhibit little or no play of colors, to very intense and lively plays of color. Mexico is the main source for fire opals. Fire opals are often labeled by the predominance of their body color, i. e., red opal, yellow opal, etc.
- Black: Also known as “dark opal”; “black” opal refers to a group of opals with a stunning and distinct play of color against a dark, or black background. Black opal (discovered in Australia in 1903) is considered one of the better grades of opal and can command high per-carat prices.
- Opal doublet: An opal doublet is a thin layer of opal cemented to a flat, often black stone such as onyx. The resulting “doublet” mimics the more expensive black opal and can be quite beautiful.
- Opal triplet: An opal triplet is an opal doublet to which a protective top layer of colorless quartz (or even glass) has been added to enhance the colors of the main opal slice.
- Opal Mosaic: An arrangement of many small, irregularly shaped pieces of multi-colored opals cemented into a pleasing pattern and set in rings and pendants.
•Shape
Opals are most often cut into round, marquise, pear, oval, or heart-shaped cabochons, or into shapes with a flat top. Opals that are all one color are sometimes faceted. In many instances, in order to preserve an individual opal’s unique play of colors, a pendant, brooch, earring, or ring mounting will be designed to accommodate the natural shape of the stone rather than cut it to fit a standard shape mounting.
•Durability
Opal is not a very durable stone. It is only a 6 on the Mohs Scale and should be treated with care. It is considered one of the “softest” of gemstones and should be handled, cleaned, and stored accordingly.
•Quality
The quality of an opal is determined by the intensity of its “fire”; i. e., the beauty and uniqueness of its play of colors. In general, pale, single color opals (also known as potch opals or white opals) are considered lower quality than the vividly colored stones. In the jewelry industry, many dealers grade opals by using these five categories:
- AAA grade: These are the scarcest stones and they have deep, very intense iridescence and fire, and boast many gorgeous colors. AAA opals are strikingly beautiful.
- AA grade: These stones have strong fire and often show several colors; they usually have a white or a clear background.
- A grade: These stones have medium fire and a few distinct colors; they also usually have a white or clear background.
- B grade: These stones have a light play of colors and may have one or two colors; their background is often very white.
- C grade: These stones have almost no play of color and are usually whitish; these opals are often used in budget-priced jewelry.
•Legend and lore
Opals are a symbol of hope, fidelity, and purity. Opals are also reputed to heal diseases of the eye; while black opals are believed to be lucky and to make the wearer attractive to other people. For centuries, opals have also been associated with spirituality and prayer.
•Care
To clean your opal jewelry, swish the pieces in a mild soap solution and rinse them under warm water. Do not soak opals in anything, especially ammonia-based jewelry cleaner. If mistreated, opals can dry out, become brittle, and break; and their colors can fade. Avoid anything that can dry out your opals, such as direct sunlight or excessive heat.
