Opal is a multi-colored stone used in many types of jewelry. Originating mostly from Australia (where it’s the national gemstone), opal is highly valuable. The two classes of opal include precious, which has an iridescent appearance created by the diffraction of light from minerals, yielding the characteristic play-of-color; and common, which is more uniform in color. It ranges from milky bluish or greenish to honey-yellow, to wood-like, brown, grey, or clear.
Formed from mineral deposits in most kinds of rock, opal is made primarily of silica. The most common types are white, gray, and green; black opal is the rarest form. Some of the finest, most-valuable opals in the world include:
Fire of Australia
Considered the finest uncut opal, it is valued at close to $900,000. The 998-gram stone is on display at the South Australia Museum. It was mined in 1946 at the Eight Mile opal field in Cooper Pedy, a small South Australian desert town, and became a family heirloom, but was loaned to the museum for safekeeping.
The Virgin Rainbow
This $1 million opal is the world’s most expensive. It was discovered in 2003 by John Dunstan (who has been featured in the Outback Opal Hunters TV show) in the same opal fields as the Fire of Australia. Another interesting fact is it formed and was found within an ancient cuttlefish skeleton. The Virgin Rainbow Opal glows in the dark. It is owned by and displayed in the South Australian Museum in Adelaide.
Found in 1938, this AUD$1 million stone is the world’s most valuable black opal. The 180-carat stone measures 3 inches by 1.8 inches and contains red, green, and blue coloring. It was dug from an old seabed at about six meters deep. On the back, there is the unmistakable impression of a starfish.
Later renamed The Fire Queen, this stone was found in November 1906 by Charlie Dunstan. It weighed in at close to 900 carats. Dunstan sold the stone for £100 to an unknown buyer, but it later changed hands several times. However, it was valued at £40,000 at the Chicago Museum after being renamed. It was resold for £75,000 to John D. Rockefeller in the 1940s.
Pride of Australia/Red Emperor
Shaped like the continent of Australia, this two- by three-inch opal is multi-colored with black and blue veins with red streaks. It had been featured at five World’s Fairs by 1954. The 225-carat stone was purchased by Ernie Sherman from miners along with three other stones for £2,000. In 1920, it was the highest price anyone ever paid for four black opal stones. In 1931, Pride of Australia was valued at this price alone. It was eventually sold for an unknown amount (estimates ranged from £50,000 to £150,000) and later stolen from Forest Lawn Memorial Cemetery in Los Angeles, CA.
The Flame Queen
It was mined in 1918 at 35 feet below the surface and through a 2½ foot wide tunnel. The original offer for the stone was £7 in the rough, which was refused, but it was later sold to a gem buyer for £93. The Flame Queen weight 253 carats and measured 2¾ inches by 2 1/3 inches, featuring a mix of red and blue-green opal and reflecting various combinations of color. It was sold for $1 million in 1980.