Opal is also known as Opal. The main mineral is opal. It also contains a small amount of secondary minerals such as quartz and pyrite, usually containing a certain amount of water. Black Opal is one of the opals. The black opal is named because the growing mother rock is black and the background color is black. It is different from the common white opal and is the highest value in opal.
Black Opal is mainly produced in the Lightning Ridge of Australia. The various black opal products are different and have different values. The important evaluation criterion of black opal is the color-changing effect. Opal usually has the typical color-changing effect in gemstones. That is, turning the opal under the light source can see colorful spots, and the colorful and prominent highlights have always been loved by the world. Usually high-quality opal color is uniform and complete, and the type and color of color change are the key to evaluation.
The more colors of opal's color change, the more vivid, the higher the value, the maximum of 7 kinds of color change colors. According to the color value from high to low, red, orange, yellow, blue, purple, green, light blue. Red has the highest value, including purple, orange and other colors, but the strong contrast of deep red, orange and black bottom is best. In addition, the more common color change of black opal is blue and green. If there is only blue and green opal, is it not the best? It is also not perfect. If you change color to give a high-quality and beautiful image, you will also have the best value. In addition, the larger the range of color change, the higher the value. If the color-changing of the stains forms a special pattern, it will be highly regarded as a collectible, such as a flag style, a peacock feather style, and the like.
In addition to color change, measuring the value of opal also includes some common elements of gemstones, such as clarity, whether there are cracks or other inclusions, weight is also the key, the higher the weight, the higher the value. Also associated with reduced production, Australia's gravel-backed opal has also begun to attract attention, black opal is attached to the parent rock, and gravel-backed opal is attached to the dark brown sandstone. The price of the gravel back opal was only one-fifth of that of the black opal, but with the decline in the production of high-quality black opal, the price of the gravel-backed opal with a beautiful color-changing effect also rose a lot. There are also producers collecting thin layers of opal, which can not be independently made into jewels of opal, with glass or black underlay, used to make sandwich opal, 3 layers of opal, etc. These are artificial gems, the value is not high.
Spandex Super Soft Flower Printing
Zebra Spandex,Snakeskin Spandex,African Print Spandex,African Print Spandex Fabric
CHANGXING JINMAOCHANG TEXTILE CO.,LTD. , https://www.jmcknittedfabric.com