Opals develop crazing if they are allowed to dry out.
In the opal cutting process the potch is ground away from areas of gem opal. The process is 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 clothes-pins, usually with dopping wax, which resembles sealing wax. This allows the cutter to manouver a stone against the cutting wheel without grinding away his or her fingerprints!
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.