(1) First-grade turquoise: It is a bright sky blue, with pure and uniform color, strong luster, translucent to slightly transparent, and a glassy surface. The texture is dense, delicate, tough, without iron wire or other defects, and the blockiness is large.
(2) Secondary turquoise: dark blue, blue green, emerald green, strong luster, slightly transparent. The texture is tough, the iron wire or other defects are few, and the blockiness is medium.
(3) Three-level turquoise: light blue or blue-white, light yellow-green, etc., poor gloss, relatively stiff texture, obvious iron wire, or more defects such as white brain, tendons, and heart, and the block size varies. .
Turquoise grade abroad
According to the characteristics of turquoise color, transparency and impurity distribution, turquoise is divided into four grades. These grades are sometimes represented by some place names. The names here only use the quality grade and do not indicate the geographical origin.
(1) First-grade products include the following three different structures of turquoise
A. The finest turquoise is strong-medium blue, soft and uniform in color, no dark or light blue spots, no iron wire, strong luster and translucency to give the turquoise surface a glassy feel. Turquoise has a small porosity and a relatively high density. This grade is rare, common in Persian-produced turquoise, so it is commercially Persian;
B. The color and texture are evenly superior, but the turquoise surface has an attractive spider web pattern, in which case the iron forms a line of lines as thin as a line. This turquoise is often the turquoise of the Persian spider web;
C, the color and texture are evenly superior, but the turquoise contains different numbers and forms of iron wire. The number, color and distribution of the iron wire make the grade of the turquoise of the iron wire vary greatly, and the attractive degree is the classification. One of the principles. This type becomes Persian-grade iron wire turquoise.
(2) The secondary products of secondary products are classified into the following three types according to their structure:
A. This grade is light blue, not as bright as the Persian color. Transparency is also worse than Persian grade, opaque or slightly transparent, the gloss is not strong enough, the structure is spotted, with slightly shallower or slightly darker areas, most without iron wires;
B, color and texture of the same level, the surface has a thin spider web;
C, color and texture of the same level, containing different quantities and forms of iron wire.
The second-class products are commercially known as the American-grade, American Turquoise and Mexican Turquoise, and these names do not have a place of origin.
(3) Three-level products
It is blue or blue-green, usually selected from the first grade. It is denser than the American turquoise, but the color is not flattering, so it rarely approaches the second grade. There is not much sales of the inferior products with a lot of stickers. Commercially known as the Egyptian class.
(4) The four-grade product is light-colored or dark-yellow-green, with more iron wires. It is inferior and has a very small value. It is commercially known as Afghan turquoise as a gemstone with color as its main feature, arts and crafts. Turquoise is required to have a standard sky blue. Followed by dark blue and blue-green, strong luster, translucent, fine texture, dense block, smooth and crack-free, no white brain, tendons, heart, explosive and other defects. Those with black patterns require clear borders and no gaps. As for the transparent small crystal, it is a rare turquoise boutique, which can be polished into a faceted gemstone with a weight of 0.6 carats.
White brain: A white or moon-white star or spot that exists on a sky blue or blue-green background. This time is caused by minerals such as quartz and calcite. The presence of the white brain greatly reduces the quality of the turquoise. Rib: refers to the turquoise with fine veins and white brain. Heart: The outer layer of turquoise is porcelain pine, and the inner part is grayish brown. The taupe is a big bogey of turquoise, which seriously affects its quality. Explosive: refers to the property of turquoise which is easy to crack naturally during processing.
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