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Opal is typically categorized based upon its body color – light or dark, as well as the degree of transparency. The body color doesn’t refer to the play of light, but to the actual color of the stone itself, which can be colorless, white, various shades of grey, or black.
Light opal includes all the shades through medium grey
Dark opal includes dark grey to black
In addition, opal can have varying degrees of transparancy, from transparent to translucent to opaque. When an opal is transparent or very translucent, and the clarity of the color is very sharp – the play of color must be both on the surface and within the stone – the opal is called crystal.
Jelly opal is a type of crystal opal that has pla of light within the stone that is hazy, rather than clear.
Because opal is a relatively soft stone, it must be taken care of in certain ways.
Because of the way they are constituted, opals tend to dry and crack. Therefore, avoid exposure to anything that is potentially drying (for example tramping around in 90 degree F weather for several hours, wearing an opal ring!).
Immerse the opal in water for several hours, on a regular basis. At one point it was the done thing to wipe the surface of an opal with oil – this practice has been discredited. Never wipe the surface of an opal with oil, or immerse them in oil…as this will cause them to lose their fire.
In addition, never clean opals in an ultrasonic cleaner. These cleaners can worsen inclusions and weaken color.
The advice about immersing your opals in water is only valid if it is a solid opal. If it is a doublet or a triplet, you don’t want to do this, as it can weaken the adhesion between the glue.
However it takes prolonged exposure to water to harm a douiblet or a triplet…. if you get caught in the rain or forget to take it off – just once!- while you’re showing, that should be fine.
Solid opal can be cleaned –gently –with mild detergent in warm water, using a soft-bristled toothbrush or cloth. Do not use bleach, or cleaners with chemicals in them. Doubles and triplets should be wiped with a damp cloth, but of course never immersed in water.
Should your opal becomes scratched, or lose its shine due to small scratches or scuff marks, bring it back to an opal cutter, who can polish it to make it look like new again.