Jin Gangzuan is one of the four most expensive gems in the world. Its greatest feature is hardness, which is the highest among all known substances. The second major feature is its high refractive index and dispersion characteristics, and high-purity diamonds will shine brightly under light.
The appearance of diamonds is similar to that of glass, crystal and artificial gem, so it is difficult to identify them. Here are eight identification methods.
(1) The reliable identification method is to measure with a thermal conductivity meter. Diamonds with good thermal conductivity are poor, not even glass, crystal or artificial gem.
(2) Diamond is the hardest substance known at present, and its Mohs hardness is 10. If there is anything that can mark the object to be distinguished, it is not a diamond.
(3) Try licking with your tongue. Because the diamond has good thermal conductivity and can transfer heat quickly, the tongue will feel very cold when licking, which is like not feeling this way. Note: The object to be identified must be clamped with tweezers before the test.
(4) Breathing test. After the object to be identified breathes, the water mist condensed on the diamond evaporates faster than that on the imitation, because the high thermal conductivity of the diamond can quickly replenish the heat and make the water mist evaporate quickly. Before the test, it is necessary to clamp the object to be distinguished with tweezers.
(5) Looking for reflected light. Observing with a magnifying glass, the finely polished diamond waistline will present a very fine matte shape, reflecting shining light. This feature of diamonds is not available in imitations.
(6) check the waist circumference. Under the magnifying glass, there are many hairlike cracks on the diamond, which is also the uniqueness of the diamond.
(7) Look at the growing mound. Observing under a magnifying glass, there are often grooves and triangular growth hills on the crystal surface of real diamonds, but these features are invisible to imitations.
(8) Diamonds are lipophilic, while the main imitations are hydrophilic. Scratching an oily stationery pen across the diamond surface will leave lines, while the ink on the imitation will gather into droplets. Another method is to use water-based strokes. Small water droplets on the surface of diamonds can last for a long time, while imitations will disperse in a short time.
There are three types of imitation:
① Ordinary glass containing alumina is mistaken for diamond because of its high refractive index and dispersion, but its hardness is low.
(2) Imitated by chemically synthesized sapphire and colorless spinel, the hardness is close to (slightly lower than) that of diamond, but the refractive index and dispersion are low, and there is birefringence, and the ghost can be seen at high magnification.
(3) Imitated with artificial cubic zirconia, it has high hardness and good refraction, and is a little yellow like most diamonds. If there is no diamond probe, it can be identified by the above method.
In addition, when the genuine product rotates, it will reflect faint yellow and blue colored light inside the torus, while when the zirconia counterfeit product rotates, it will reflect more colored light inside the torus, which is far less polished than the diamond, but the torus is regular and has no defects inside. If the real drill is less than 3 mm, the cutting is irregular and there are some defects inside.
Identification of two kinds of fake diamonds
Diamond is the king of precious stones, and its value is extremely high. So there are many fake diamonds on the market, and zircon is one of them. Zircon looks like a diamond. Its chemical name is zirconia, which was first synthesized by chemical method in the former Soviet Union, so it is also called Soviet diamond. Its hardness, density, refractive index, transparency and sparkle are almost the same as diamonds, and the colorful phenomenon is sometimes stronger than diamonds. The other is natural zircon, whose flash degree and color are similar to those of diamonds. Their value is very low, which is very different from real diamonds.
(1) natural zircon
The chemical composition of natural zircon is ZrSiO4, which is a transparent or translucent square short column crystal with red, orange, brown, green, blue, gray, colorless and other colors. Colorless and transparent zircon looks like a diamond and is called gem-grade zircon. Some countries call it fake diamonds, American diamonds, and the United States calls it Bangkok diamonds. Its main producing areas are Thailand, Sri Lanka, Tanzania, Cambodia, the United States and Australia. China is also rich in mineral resources.
(2) artificial zircon
The symbol of zirconium is Zr, which is a silvery-gray glassy metal that is oxidized into zirconia. The former Soviet Union developed cubic zirconia in the 1970s, which looks like diamonds, that is, artificial zircon, also called cubic oxidation or Soviet diamonds. Since 1980s, the output has increased sharply, and it has flooded the international market because of its low price and similarity to real diamonds.
Cubic zirconia, colorless and transparent, has a strong luster, like a diamond. Its dispersibility is obviously higher than that of diamond. The facets at the bottom of the ring face are often orange, red and sunny, dazzling, soft and gorgeous. Therefore. Cubic zirconia has the brilliance of diamonds. If the corresponding trace pigment ions are added when making cubic zirconia crystals, orange, rose, yellow, purple and green can be obtained. Cubic zirconia has high refractive index, good high temperature resistance and chemical stability, which is similar to diamond. Therefore, it is difficult to distinguish cubic zirconia from diamond by grinding torus. However, it can be distinguished from diamond in terms of relative density and hardness. Compared with diamonds, cubic zirconia has another distinguishing feature, that is, when grinding, because of its small hardness and uniform waist circumference, you can see the scratches left by the grinding disc. Observing the inside of the crystal with a microscope, we can see the clastic zirconia powder and a small amount of bubbles left after melting. Cubic zirconia has no fluorescence when irradiated by fluorescence and is opaque when irradiated by X-ray. However, diamond is light sky blue under ultraviolet fluorescence and transparent under X-ray, which is easy to distinguish from cubic zirconia.
(3) Zircon impersonates diamond.
Some jewelers are mystifying, and often give zircon some strange and mysterious names, so that customers can't understand, understand and confuse it, so as to sell the real thing at a high price and make huge profits. For example, write "Zalgun Diamond", "Zr", "American Diamond", "Bangkok Diamond" and "Soviet Diamond" on the label to make customers think that diamonds are produced in the United States, Thailand or the former Soviet Union. In fact, "ZARGUN" is the Arabic name of zircon, "Zr" is the symbol of chemical elements of zirconium, while American diamonds, Bangkok diamonds and Soviet diamonds all refer to gem-grade zircon or cubic zirconia in the international market.
In jewelry stores in western countries. All the ornaments inlaid with cubic zirconia are marked with "artificial gem" or "Zircon", which are as cheap as children's toys. In order to accurately identify this kind of fake diamond, it must be detected by thermal conductivity meter.