Turquoise classification
Turquoise is usually classified according to its origin, color, luster, texture, structure and structure, and many classifications extend to the quality grade of turquoise more or less, which has hierarchical significance.
By color
A. Blue-green stone: blue, opaque block, sometimes dark blue;
B, Palablueturquoise: light blue, opaque block;
C, turquoise: turquoise, opaque block;
D. Turquoise: green, opaque block;
E, yellow-green turquoise: yellow-green, opaque block;
F light green turquoise: light green, opaque block.
By region
A, NiShahpour turquoise: produced in NiShahpour area on Ali Scrooge Mountain in northern Iran. China was called "Hui Electron" in ancient times, and Japan and other countries called it "Oriental Turquoise".
B. Sinai Turquoise: Located in the Sinai Peninsula, it is the oldest turquoise mine in the world.
C. American turquoise: produced in the southwestern States of the United States, especially Arizona.
D, Hubei turquoise: turquoise produced in China and northwest Hubei, called Jingzhou Stone or Xiangyang Dianzi in ancient times. Hubei turquoise is famous at home and abroad for its large output and excellent quality. Mainly distributed in Yunxian, Zhushan and Yunxi in northwest Hubei. The mine is located in the western end of Wudang Mountain and some areas south of Hanshui River.
There are Egyptian turquoise, Chilean turquoise, Australian turquoise and so on. However, some names of origin not only represent the origin, but also represent and indicate the quality grade of turquoise, so these names also have the meaning of quality grade.
By structure
A. transparent turquoise: refers to transparent turquoise crystals. Very rare, only produced in Virginia, USA, the polished transparent gemstone weighs less than 1 carat;
B, massive turquoise: refers to dense massive turquoise with bright color, fine texture, toughness and smoothness, which is the main material of jade carving and quite common;
C. Tuberculous turquoise: refers to turquoise in spherical, ellipsoidal, grape-shaped, pillow-shaped and other shapes, and the size of nodules varies greatly;
D. Blue turquoise: also known as "lace turquoise", it refers to the turquoise that forms a spider's net pattern due to the existence of iron;
E, wire turquoise: refers to the turquoise with fine iron-black flowers on the surface;
F. Porcelain turquoise: refers to turquoise with sky blue, dense and tough texture, extremely bright fracture such as porcelain fracture after crushing, and good quality;
G vein turquoise: refers to vein turquoise produced in the fractured zone of surrounding rock;
H, variegated turquoise: refers to turquoise with speckled and star-shaped structure due to the presence of kaolinite, limonite and other substances, with poor quality;
1. Loose surface: refers to loose turquoise with granular fracture and low hardness, which can be scored with nails. Some blocks are available;
J, bubble pine: refers to the turquoise softer than powder, inferior, and cannot be used as jade carving material. However, after artificial coloring and glue injection, this turquoise has become an optimized turquoise variety.
How to identify turquoise
Identification method of natural turquoise;
Natural turquoise is usually modified by wax injection, dyeing and injection molding, which is generally recognized by the jewelry industry. After all, there are too few high-quality turquoise.
1, dyeing
(1) dyed turquoise is unnatural. Turquoise dyed in the domestic market is often dark blue or dark green, which is too uniform, but the color becomes darker at the crack.
(2) The dyed turquoise is very light in color, generally around 1mm, and light-colored nuclei may be exposed in some places.
(3) Wipe with cotton ball dipped in ammonia water, which can be stained with blue-green.
2. Spray molding method
Injection molding includes injection molding of colorless and colored plastics, and the turquoise after injection molding can be identified by the following points:
(1) refractive index: Generally, injection molding will be lower than 1. 1.
(2) Relative density: The relative density of injection molding is relatively low, generally less than 2.76.
(3) Hardness: The Mohs hardness of injection molding is generally 3-4, and the injection-molded turquoise is prone to scratches.
(4) Hot needle test: Injection molding will produce special pungent smell and burn marks.
(5) Infrared spectrum: We can observe the strong absorption between 65,438+450 cm and 65,438+500 cm caused by plastic, while the new injection-molded varieties have a strong absorption band of 65,438+725 cm.
Turquoise price:
At present, there are many factors that affect the price of turquoise in the market, and each factor has a certain influence on the price, among which the most important ones include the color, texture and fragmentation of turquoise. Only turquoise is mentioned here, but only one kind of turquoise includes blue turquoise, light blue turquoise, blue turquoise, green turquoise, foam and so on. The best quality is blue or dark blue, and the price is the most expensive.
Turquoise can be divided into transparent turquoise, massive turquoise and wire turquoise according to its texture. The more opaque or slightly transparent the turquoise, the better its quality and the higher its natural price.
Turquoise can be divided into glossy and dull according to gloss. Of course, the higher the gloss, the better.
Combined with the above situation, the international gem circle divides turquoise into four grades: the first grade is also called Persian grade, the second grade is American grade, the third grade (Egyptian grade) and the fourth grade (Afghan grade). Among them, the first-class product is the best, and the price can reach several thousand yuan. Of course, the turquoise we bought in the general market may not be by going up one flight of stairs. The price of turquoise like that ranges from one gram in 40 yuan to 80 yuan, and a slightly better one may cost several hundred yuan. Most of these turquoise have been artificially optimized and have little collection value.