The terms are often used synonymously, but this writer shows that ' potch is found only in association with precious opal and differs from common opal in its structure quite substantially.
I do still think opals are stunningly beautiful and precious to many people though. This could be a factor in the valuation and designation of precious vs semi-precious. In the case of opal triplets, a colorless glass or crystalline cap is cemented to the opal slice. To recap, here are the key differences between Ethiopian opal vs. white opal: Color - White opal is milky white, whereas Ethiopian opal comes in a variety of body tones from blue to black to yellow. However, there are three notable types of opal (precious, common, and fire), each with different optical effects, so the intended meaning varies depending on context.
Discusses the difference between potch' opal and common opal.
Milk Opals were called the milk drops of the Mother Goddess in a number of cultures, and serve as special talismans of protection, nurturing and support. Opalescence refers to the optical phenomena displayed by the mineraloid gemstone opal (hydrated silicon dioxide).
Milk Opal - generally Common Opal, though the name is sometimes applied to milky-white Precious Opal, or cloudy Opal with a light background. 90 % of World's supply of opal from South Australia Assembled Opal Products Doublets and Triplets: Doublets and triplets consist of a thin slice of opal cemented to a dark substrate. Recent data suggests that the world supply of precious opal may have changed.
Precious opal vs Potch opal Each local opal field or occurrence must have contained voids or porosity of some sort to provide a site for opal deposition. Australian opal has often been cited as accounting for 95-97% of the world’s supply of precious opal, with the state of South Australia accounting for 80% of the world’s supply. Opal is the national gemstone of Australia. In volcanic rocks and adjacent environments, the opal appears to fill only voids and cracks, whereas in sedimentary rocks there are a variety of voids created by the weathering process. On the other hand, it seems to me that some opals are particularly susceptible to cracking or other negative outcomes due to the water content and other minerals. Rarity - White opals are much more common than Ethiopian opals, which … Precious opal and common opal can be shaped and polished in a rock tumbler. Be warned before you try it that this is a great way to waste a bunch of nice and often expensive opal if you don't know what you are doing or if you don't pay careful attention to what is happening in the barrel. * 1996 , , …