Opal: Nature's Fireworks
 

Mysterious opals contain the wonders of the skies - sparking rainbows, fireworks, and lightning - shifting and moving in their depths. Opal has been treasured throughout history around the world.   Roman historian Pliny described the beauty of opal as the combination of the beauty of all other gems: "There is in them a softer fire than the ruby, there is the brilliant purple of the amethyst, and the sea green of the emerald - all shining together in incredible union. Some by their splendor rival the colors of the painters, others the flame of burning sulphur or of fire quickened by oil." Opal was much loved and valued highly by the Romans, who called it opalus.
 

Opal was also treasured in the Middle Ages and was called ophthalmios, or eye stone, due to a widespread belief that it was beneficial to eyesight. Blonde women wore opal necklaces to protect their hair from losing its color. Some thought the opal's effect on sight could render the wearer invisible. They were recommended for thieves!

Opal is cut in Australia, Hong Kong, Mexico, Germany, and other places.  The hardness of opal ranges from 5.5 to 6.5 on the Mohs scale. It should be protected from heat and strong light, which can dry it out, causing cracks. Ultrasonic cleaners, metal polish, acids, and any strong solvents should be avoided. Exposed corners or points on pear or marquise shape opals may chip if hit while they are being worn. Opal is best set in a protected mounting.