Opal is the birthstone of October. It is classified as a "phenomenal" gemstone because of the play-of-color that some types of opals possess. This play-of-color is different on every stone, depending on the body color, which can be almost any hue, and it can be either transparent, translucent or opaque.
Play-of-color occurs when light interacts with precious opal's orderly arrangement of silica spheres. As the light waves travel between the spheres, the waves bend. And as they bend, the break up into spectral (rainbow) colors, causing the play-of-color.The most prized of these colors are red, orange, blue and green. The flashes can occur as small dots or can be large, and brush stroke-like, across the face of the stone.
Most precious opal comes from Australia, including the precious black opal. This type commands the highest price of all and usually sell by the piece rather than by the carat. These opals have a dark grey background color which can be opaque, translucent and even transparent.
White opal has a white translucent to opaque background. This opal makes up the bulk of commercial opals and is the most familiar type. You can find commercial qualities in pale and cloudy yellows or browns with faint, scattered play-of-color as well as top quality almost transparent gems which can have distinct patterns of crisp, lively play-of-color.
The pattern is the arrangement of the play-of-color. The industry uses three general catgories: pinfire, which are small patches or dots, flash, which are large areas of the play-of-color, and harlequin, which are large, distinct, usually rectangular patches with the edges touching each other. Harlequin patters are the most desirable.
Some opals can be assembled in to doublets or triplets. The doublet have a gemstone base, usually black chalcedony, to which the opal is attached. The triplet has the gemstone base and also a piece of crystal quartz on top of the opal to protect it.
There are also synthetic opals on the market as well as imitation opals made of plastic which can be effective and affordable alternatives to the real thing. These can be separated from the real gemstone by a gemologist using a 10x loupe or a microscope.
In the world of metaphysics, opal is considered to be a a stone of inspiration which can enhance imagination and creativity. It helps one release inhibitions and it can enhance memory. Opal is also a very spiritual stone, and can help one be "invisible" in situations where they don't care to be noticed. Opal brings happy dreams. It also eases the process of change. Physically, opal is said to be helpful for eyesight and Parkinson's disease.
By: Pamela McCombs
PZM Designs
