| Author: Editor Big Head
Opal :Opal
Composition: Hydrated silica gel
Crystal structure: amorphous
Hardness: 6
Optical properties: refractive index 1.37-1.47, unmatched refractiveness
Specific gravity: 2.10
Opal rough
Opal is arguably the most varied and interesting gemstone.
The basic composition of opal is silica (watery), which is the same as crystal and chalcedony, but the crystalline pattern of the three is different. Crystal is crystalline, crystalline large enough to be visible to the naked eye, chalcedony is cryptocrystalline, which must be seen under the microscope, and opal is amorphous, completely crystalline, which also makes its specific gravity and hardness smaller than the other two.
The biggest feature of opal is its play of Color. Under the illumination of the light, the opal can be seen, red, orange, yellow, green, blue, indigo, and colorful spots, which are gem effects that no other gemstone has, and make opal lovers call it the most beautiful gemstone.
In addition, although relatively small, there are also varieties of opals that have not changed color to form gemstones, and the body color is the reason for its popularity, common ones are fire protein (red to yellow), blue opal, pink opal.
Fire protein
Blue protein
Powder protein
The color of opal with color change can be divided into two parts, the first is its body color, and the second is play of color. And its value is also judged according to these two parts.
The main color of opal, the more common is white, black, orange-red, transparent and colorless. White opal is more common on the market, and if there are no color spots on albumin, it is called potch and has no commercial value.
Black opal is generally considered more valuable because the color change on it is particularly bright under the black body color.
Melanin
But usually, the so-called black opal does not have to be inky black, as long as the body color is dark, it is generally classified as melanin.
The body color of the transparent opal is called crystal Opal (CrystalOpal), if it has a bright color change, it is also a quite popular opal variety. The transparent opal produced in Mexico, whose body color is particularly clear, is called water opal (water opal).
While the value of a gemstone in general comes in large part from its weight, opal does not, and its color change factor is more important than its weight factor. Therefore, even if the smaller opal, if the color change on it is strong and beautiful, the price may be more than ten times more expensive than the larger but not strong color change opal.
In general, red spots are rarer and more expensive than blue-green spots, in addition, the larger the area occupied by the spots, the higher the value.
Protein petrified wood with alkyxated wood grain
To show its color, opals are usually not made into faceted gemstones, but are ground into a convex shape. In addition, due to the low hardness and certain toughness, opals with less bright color changes are also suitable for carving.
Opals often see the phenomenon of invasion and substitution, which is related to its amorphous properties. The so-called substitution refers to the fact that when the fossil is buried in the ground, there are opal veins passing through, and the original fossil components are replaced by the components of the opal bit by bit, but the rock block itself still maintains the texture of the fossil. Australia's opal mining areas are originally covered by seawater, so many shells are also produced by proteins.
The intrusion phenomenon is formed when the opal vein passes through the deposit and the flowing opal enters the crack of the deposit. Cutting and polishing this opal into rough from iron or other deposits will give it a special pattern. Because it still contains parts of the parent rock, this opal is called boulder opal. If the opal on the boulder back forms an interlaced pattern, it is sometimes called Matrix Opal, or Picture Opal.
Opal Rock Formations
Non-colored opal, although generally referred to as wave opal, is considered to have no commercial value, but some of them are accepted by the market, and in addition to the aforementioned fire protein, there are also blue and pink opals. Blue opal is similar in color to silica malachite, with a bluish-green color, but with a lighter specific gravity and opaqueness. Pink opal is darker than commonly known as pink gemstones , more like the color of rhodochrosite , sometimes with fine black lines , and is opaque on the body.
When considered from the direction of making jewelry, opal has two disadvantages, one is that the hardness is too low, only about 5 to 6, which is easy to wear when worn; the other disadvantage is its moisture-bearing characteristics, which make it easy to deteriorate when processing and heating, causing the color spots to disappear or produce cracks.
Because opal may be cracked due to lack of water, after mining, the opal will be placed in a normal environment for several months, and it is determined that its texture is relatively stable and will not produce cracks, and it will be used as a gemstone. The so-called opal should be raised in water, which actually refers to opal with poor texture.
However, jewelry made of opals is safer to avoid being in a high-heat environment.
Overall, although it is difficult to process, opal's remarkable color change is unmatched by other gemstones, making it quite popular.
This is a fairly high grade opal,
Its body is translucent, and all the colors that can be seen on the picture are the color of the opal
Is opal cheap? This is not the case.
A very good quality opal is worth a lot, hundreds of thousands of yuan or more than a million yuan is also organically visible, although the domestic market does not know it deeply, but like all gemstones, all high-end grades have their price increase space, after all, in the reality of [digging one less], high-grade opals have gradually knocked open the hearts of jewelry investors.
A white orbal carved into a maiden's head
In the past, opal was one of the gemstones of the imperial family, and ordinary people could not and could not have it. Today, it has been able to transform into a gemstone that can be enjoyed by the general public thanks to the extensive discovery of opal mines in Australia. In 1993, the Australian government designated the opal as the national stone, which also made it another representative of Australia after the koala and the kangaroo. In terms of production, 96% is concentrated in Australia.
Opal is a combination of water-rich silica, its hardness is not high, about 5-6.5 degrees, so it is better to avoid scratching or drying in preservation or use, these characteristics are similar to pearls. According to research, opals were formed between 2000 and 300 million years ago, and to destroy an Australian opal requires heating to more than 260 degrees Celsius. Opal is best valued for complete ores, which can be made into gemstones or carvings, etc., but in special cases, when it is still a molten silica liquid, it may be combined with any material, such as trees or other ores.
The beauty of opal lies in its rainbow phenomenon, which has been explained by the phenomenon of color spots or playing color. The value of opal is determined by the distribution of the base color and the color of the game, generally the value of melanin is the highest; in terms of play, red is the most pleasing, and the value of the distribution is arranged in order of block arrangement higher than bar arrangement and dot arrangement. Because of the high market value of black opal, there have also been processing methods to blacken it to increase its value, the most common called [sugar processing Sugar Treated Matrix], which uses sulfuric acid and sugar chemical reaction to produce black. When acquiring opal, should also pay attention to whether it is artificial or sandwich treatment? Due to the continuous improvement of artificial opal technology, the difficulty of identification has also increased a lot compared with the past; its structural structure can be observed with a high-power microscope during identification to distinguish the difference from natural products, and infrared scanning can also be used to assist in identification.
Opal invades the shell and is wrapped in a shell,
This small piece of shelled opal,
Zoom in on the photo to reveal a very high-quality color change
High-end opals have also made their mark at international auctions, making them ideal for collecting. If you just want to petrify the protein as an ornament, you can choose an opal flake with a price of about 30,000-50,000 yuan, and the ring will have a good effect; if you want to make a brooch or improve the grade of the gemstone, the budget of more than 100,000 yuan is not saved. In terms of opal jewelry works published in magazines, a slightly larger and brightly colored opal, as little as hundreds of thousands of yuan, needs to cost millions, etc., I am afraid that it is a gem treasure that a few people will have. It is worth mentioning that opals can be carat or pieces of Piece when trading, so often the market will be slightly more space, it is recommended to confirm the quality before purchasing, and then negotiate.
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