Working with gem-quality Opals
Care must be taken when
polishing and setting opals. Despite their hardness, they are prone to crazing
and cracking, and loss of water content causes a noticeable loss of iridescence.
To prevent this, opals are normally stored in moist cotton wool or cloth until
it is time to work with them. Sometimes, an opal that has lost its opalescence
may be "rejuvenated" by rehydrating the stone with water or special
oils, but this may only temporarily improve the stone's appearance.
In the opal cutting process the potch (a kind of mineral crust) is ground away
from the presentation areas of the gem opal. This process unlike diamond mining,
where the blueground (Kimberlite) is crushed away from the diamond crystals.
Individual opals are "dopped" -affixed to the ends of wooden dowels
about the size of old fashioned wooden clothespins, usually with dopping wax,
which resembles sealing wax.
Grinding and polishing of opals is done under a cold water drip to prevent the
stones from overheating and cracking. A series of grits is used, from coarsest
to finest, to produce the desired finely polished surface that reveals the full
play of color in the opal.
Most gem opals are ground to a highly polished convex oval shape called a "cabochon."
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J. Thomson Custom Jewelers
5770 NW Expressway, Suite 101
Oklahoma City, OK 73132
(405) 495-6610
FAX (405) 728-1914
Email: gems@customfinejewelry.com
Copyright 1994-2005 J. Thomson Custom Jewelers