• Opals displaying play of color are known as precious opals, and opals lacking play of color are known as common opals.
• Best known for their multi-colored appearance it’s really the unique play of color that gives opals their beauty. This play of color consists of iridescent color flashes that change with the angle at which the stone is viewed. This phenomenon is also known as opalescence.
• The body color or background color of the opal defines the overall appearance of the gemstone. The two main body colors are black, opals with a dark blue, dark green, or black background and white, opals with a light colored background such as white, yellow, or cream.
• Dozens of opal varieties exist, but only a few (like Fire Opal and Boulder Opal) are universally recognized.
• The name of this, the traditional October birthstone, is believed to have originated in India (the source of the first opals brought to the Western world), where in Sanskrit it was called upala, a “precious stone."
• The name “opal” may have originated from the Greek word opallios, which meant “to see a change in color.”
• The Roman scholar Pliny used the word opalus when he wrote about this gemstone’s kaleidoscopic “play” of rainbow colors that could simulate shades of any stone.
• Opal’s classic country of origin is Australia.
• Since opal was discovered in Australia around 1850, the country has produced 95 percent of the world’s supply. Opal is also mined in Mexico, Brazil, Honduras, Ethiopia, the Czech Republic and parts of the U.S., including Nevada and Idaho.
• Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “outback.” The showers soaked deep into ancient underground rock, carrying dissolved silica (a compound of silicon and oxygen) downward. Once the water evaporated solid deposits of silica were left behind in the cracks and between layers of rock forming opals.
• With a hardness of only 5.5 to 6 on the Mohs scale, opal is a delicate gemstone that can crack or “craze” under extreme temperature, dehydration, or direct light.
• Opal doublets, often used in jewelry, are thin slices of precious opal glued onto a base material.
• Opal doublets are sometimes coated with a thin layer or dome of clear quartz to make them more resistant to scratches (since opal is a relatively soft gem). These are sometimes called opal triplets.
• Opal is the stone given to celebrate the 14th wedding anniversary.
• Opal is the traditional birthstone for October

Website by Sonia McDowall