10. The other-worldly rainbow of colors seen in Opal are called its Play-of-Color, and while it may once have been believed to be caused by Magic, Gemologists now know that the play-of-color is caused by Opal’s amorphous crystal structure which resembles a stacked arrangement of ping pong balls. The colors you see are caused by light diffraction from the orderly arrangement of spheres. Only Opal with an organized structure of spheres of the same size will show play-of-color and be considered Precious Opal. Opal that does not show play-of-color is known as Common Opal.
9. Opal’s hardness, or its ability to resist scratching, is rated at 5.5-6.5 on the Mohs Scale. What this means to you is that Opal is very soft and great care must be taken in wearing it. When you consider that dust can contain Quartz which has a hardness of 7…Opal can get scratched without you even realizing.
8. Opal is one of two birthstones for October, the other being Tourmaline. Throughout history there have been many superstitions concerning Opal, though there are as many examples of Opal being considered a Lucky Stone as an Unlucky one.
7. There are several different varieties of Opal, but only a few of them are regularly used in fine jewelry; Australian, Ethiopian, Boulder Opal, and Fire Opal, the Opals that show play-of-color.
6. Opal contains anywhere from 3 to 21% water!!! This is the result of how Opal is formed - essentially by a watery silica solution that drains into the earth, filling recesses, and then evaporating out, leaving the silica behind to crystalize. Note: These recesses can include fossils so that if you wish you can find opalized clam shells, petrified wood with opal, and even whole opalized lizards!
5. Don’t be fooled! There are synthetic opals that look natural, imitation opals made of glass and plastic; there are Opals enhanced by wax and oils to stabilize them and change their color, even smoke is used to make black opal, and still other methods to make you believe you have something finer than you do. If you don’t know what you’re looking for, you can be easily fooled.
4. Rising in popularity is the relatively new Ethiopian Opal. While Australian white and black Opals still command higher prices, Ethiopian Opal can be found in larger sizes, with even more play of color, and has the stable ability - unlike the Australian Opals - to be faceted.
3. Remember that Opals contain water. Don’t let it dry out too much!!! Have you ever looked into a case of Opal jewelry and seen Opals with cloudy areas and fine cracks? This is called “Crazing” and is the result of Opal drying out and losing its water content. So, don’t leave your Opal jewelry in a hot car or under lights for too long.
2. Opal is extremely sensitive to heat. Never use an ultrasonic or steam cleaner to clean your Opal jewelry. A safe method for cleaning your Opal jewelry is with a soft toothbrush and warm water. Treat your Opals like you would fine Pearls.
There is so much to be known about Opal. So many different varieties, sources, and value factors. Even the Common Opals have an allure worthy of use in jewelry. If you love Opal, do your research, and you might discover an Opal variety that you would love to own. When you know what you want, come back to FROM GEMS TO JEWELRY and contact Me - I know how to find what you’re looking for.