October Birthstone – Opal
Opal – October Birthstone
and for the 12th wedding anniversary
A truly fascinating gemstone with its mesmerizing display of colors that reflect the colors of the rainbow. In ancient Greece, it was believed that opals were from Zeus’s tears which were transformed into fiery opals after his victory over the Titans. They also thought opal would keep blonde hair beautiful and would fend off grey hair.
Opals are graded on three different aspects regarding quality:
- Color refers to the overall background or body color and play-of-color
- Patterning of the play-of-color
- Overall clarity in regards to opacity and amount of visible inclusions
With color, opals can exhibit a single body color such as white, with one or several colors to many colors which are exhibited when the opal is turned or tilted. The actual cause of color is created by microscopic impurities floating within the silica grid crystal structure that are part of the opal’s composition.
The mineral composition of an opal is hydrated silica and, of that, N opal can contain up to 20% water. So, imagine, all these grids of silica spheres within an opal all flashing different colors. This is the magic of opal.
Play-of-color is an important grading factor, the more colors and richness of the colors the more desirable the gemstone is.
Patterning of the opal’s play-of-color has several common terms:
- Peacock, which is mostly green and blue
- Pinpoint or pinfire, which is used to describe closely set flashes of color
- Flame pattern, which exhibits a broad flash of reddish colors
- Mosaic or Harlequin, which is a distinctive pattern recognizable by the vibrant patches of color that sweep across the opal
The clarity or transparency of an opal is based on the lack of inclusion. This can be misleading in that an opal may appear somewhat opaque but very colorful and lively and it really depends on the type of opal. An Australian black opal may appear opaque yet magnificent in its display of color while a Mexican fire opal will appear transparent with a completely different play of color.
We often see opal cut in a “cabochon” or dome style as this exhibits the gemstone to its best advantage. Opal is also used in decorative inlay work as we see in Native American jewelry. It takes a skilled lapidary or stone cutter to create a beautiful gem from a piece of rough found in the earth and at another level, a very skilled stone setter to work with opal to enable the opal to show itself to its best advantage.
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