Identification of diamonds
Diamonds are the hardest natural substances. A diamond can carve any other gem, but no other gem can carve a diamond. You can also use a "standard hardness tester" to score, and any hardness below 9 degrees is a fake diamond. Diamonds are also lipophilic. If you draw a line on the surface of a diamond with a pen, it will become a continuous straight line, while other gems will break intermittently. The above methods have certain reference value for identifying diamonds. You can also observe it through a magnifying glass with a magnification of 10. Under the magnifying glass of 10 times, you can see that most diamonds have triangular growth lines, and the surface of diamonds has "red, orange and blue" fire light. Radiant. The most accurate and reliable method is to measure the thermal conductivity data with a "thermal conductivity meter" to distinguish between genuine and fake diamonds, but the "thermal conductivity meter" is expensive.
Because diamonds are the first noble and luxurious ornaments, it is not uncommon to replace or pass off diamonds with cheap gems, artificial gem and even glass. Common fake diamonds are as follows: ruby | sapphire | natural gem | semi-precious stone | precious stone &;
① Zircon: Very similar to diamond, it is the best substitute for diamond. The identification method is that zircon has polarization and large birefringence. Observing the processed zircon prism surface with a magnifying glass of 10 times, it can be seen that the bottom edge line has obvious ghost, but the diamond has no ghost phenomenon.
(2) Glass: The refractive index of glass is very low, and there is no flickering color light like diamonds; Especially when it sinks into the water, the glass product loses its luster and immediately shows clues.
There are questions and answers about colored gems. Do you have any questions about colored gems? Welcome to write down your questions. Everyone * * * came together to ask for answers about red rubies such as Burmese, Vietnamese and African rubies, blue rubies such as Burmese, Tanzanian and Sri Lankan sapphires, and yellow rubies such as Thai, Australian and Sri Lankan sapphires. To increase their value. Introduction of gems of origin and national mining areas. , the content is an article introducing all kinds of precious stones.
(3) Soviet diamond: cubic zirconia, first developed by the Soviets, hence the name. Soviet diamond is a synthetic compound, but it is very close to natural diamond in dispersion and refractive index, and it also has an attractive "fire" light appearance. But its hardness is low (8.5), so it can be distinguished from diamonds. Moreover, the thermal conductivity is much lower than that of diamond, so it can be identified and distinguished accurately by "thermal conductivity meter".
④ Crystal: Although crystal is a transparent crystal of natural minerals, it looks like a diamond after processing, but it lacks the colorful light of diamond.
Identification of ruby
There are "ten Hong Jiu cracks" in natural gemstones, and natural rubies without any flaws and cracks are extremely rare. Artificial rubies have the same color, few internal defects or crystal inclusions, and are clean and large. As a precious gem, natural rubies over 3 carats are very rare in the market. If you encounter a big ruby, you should pay attention, because the value of natural ruby is thousands of times higher than that of artificial ruby. A little carelessness will "take medicine."
Natural ruby has a strong "dichroism". The so-called dichroism means that there are two colors of red and orange red from different directions. If there is only one color, it may be red spinel, garnet or red glass.
Red spinel and natural ruby are very similar, and they are most easily confused, so be very careful.
Sapphire identification of Asian jewelry net
Natural sapphires are often uneven in color, and most of them have a flat growth line. Artificial sapphires are of the same color, and their growth lines are arc-shaped strips, and they are often breadcrumb-shaped or beaded bubbles in the body.
Natural sapphire also has obvious dichroism, one direction is blue, and the other direction is blue-green. Other gemstones are different in color from natural sapphires and can be distinguished.
In addition, the simplest method can be hardness measurement. Natural sapphires can carve traces on topaz, while other sapphires are difficult to carve traces on topaz. Therefore, when buying jewelry, if there is no instrument around, as long as there is a topaz, sometimes some problems can be solved.
Identification of jadeite jade
In nature, there are many kinds of green transparent gemstones similar to emeralds, such as jadeite, tourmaline, fluorite, olivine, garnet, zircon, etc. Among them, tourmaline, fluorite and jadeite are easily confused because of their similar appearance to emeralds. Visually, green jadeite is generally translucent, often in a patchy structure with interwoven fibers, while high-quality emeralds are transparent and crystal clear. Emerald hardness is 7.5-8, while fluorite hardness is very low, only 4. Emerald accounts for a small proportion, while fluorite, tourmaline and jadeite account for a large proportion. Zircon has strong dispersion and obvious ghost.
In addition, there are artificial emeralds and green glass similar to natural emeralds. The biggest difference between them is that most natural emeralds have defects or inclusions, which shows dichroism. Of course, in order to distinguish strictly and correctly, it is best to use identification instruments such as optometry and polarizer.
Identification of cat's eye
In recent years, there is a kind of glass fiber cat's eye ring on the market, which is embedded in gold or silver rings, making people unable to tell the true from the false. The identification method is that when the torus is rotated, several light bands can appear at the arc top of the fake cat's eye at the same time, while there is only one real cat's eye. The fake cat's eye eyeliner is rigid, while the real cat's eye eyeliner is flexible. True cat's eyes are mostly brownish yellow or light green, while fake cat's eyes are varied in color, including red, blue and green.
Identification of opal
Opal can be divided into black opal, white opal and yellow opal by color, of which black opal has the highest price. In order to improve the low-priced white or yellow opal, some people change its color artificially and become "black opal" in order to make high profits. The main method is to boil with sugar or inject plastic to make the white opal black. The identification method is that the specific gravity of opal is obviously different after boiling sugar or injection molding, and the specific gravity value becomes lighter when tested in water. The heating needle can also be used to test the injected opal. Natural opal can't be pierced by hot needles, but injected opal can be pierced, and it will produce the smell of plastic melting.
Identification of tourmaline
Tourmaline is a kind of mid-range gemstone, but because pink and bright blue tourmalines are more expensive, there are also imitations. There are two common imitations, one is artificial coloring with colorless tourmaline; One is made of red glass. The identification method is that the real tourmaline often has obvious dichroism and can be seen as a ghost; Tubular inclusions or cotton wool can be seen in the body, and the crystal cross section is curved triangle. These characteristics are not possessed by imitations. The tourmaline dyed by workers is not difficult to identify because its color is dull and there is no "treasure light" of natural tourmaline.
Identification of crystal
Rock crystals are clear and transparent, often containing cloud, star or flocculent gas-liquid inclusions, and often with microcracks. In addition, the rock crystal is polarized, and you can see the phenomenon of twin crystals, such as a crystal ball. Looking down from the top, there will be a double image. Synthetic crystal or glass products are uniform and pure in the body, without cracks, and often have small bubbles inside. Looking down at the sphere, you can't see the ghost of the line below. With the touch, you can feel that the proportion of synthetic crystal is greater than that of rock crystal; Crystal stone feels cold and glass feels warm.
Identification of olivine
Olivine is a low-grade gem with yellow in green, similar to olive color. The most common counterfeit olivine on the market is made of stained glass. The main difference between the two is that olivine has obvious "double shadow", but glass glass does not; Crystal inclusions are often seen in olivine, and only bubbles are contained in glass. Olivine has a specific gravity of 3.5 and a hardness of 7, which is greater than that of glass (2.6) and hardness (6).
Pearls are divided into natural pearls and cultured pearls, and cultured pearls are divided into seawater pearls and freshwater pearls. Natural pearls are low in output and expensive; Moreover, cultured pearls can be produced in large quantities, so the price is much lower. The main difference between them is that natural pearls and cultured pearls have no nuclei. The inner core of natural pearls is often just some sand or parasites, or even no inner core. However, the inner core of cultured pearls is artificially made large round beads, so the outer coating is thin. On the body surface, natural pearls rarely roll because of their random growth environment and poor roundness. The inner core of cultured pearls is round, so the roundness of pearls is better. Natural pearls are transparent because of their long growth time, delicate texture, thick nacre, smooth skin and few "convex bubbles". The cultured pearls are thin in layer, rough in texture, waxy in luster, and often have some uneven "bubbles" on the surface, so the transparency is poor. If it is a perforated pearl, observe the hole carefully with a magnifying glass. If it is a cultured pearl, you can generally see a brown boundary inside the pearl, which is the boundary between the inner core and the pearl layer that grows later.
At present, imitation pearls often appear in the market, which are generally made of glass beads coated with fish scale powder or silver powder. Their luster is obviously different from that of real pearls, and their weight is also different, so people with a little experience can identify them. If you scrape off a nail or a knife, the true face of Lushan Mountain will be revealed immediately.
The jewelry industry has some experiences in identifying pearls, which are introduced as follows:
(a) the color, size, shape and luster of the beads. They are all identical, that is, artificial pearls. Because real pearls can't be consistent anyway.
The luster of real pearls is like a rainbow, colorful and very beautiful. Fake pearls are dull and have no colorful rainbow tones because of the coating on their surfaces.
③ Real pearls have good transparency, while fake pearls have poor transparency.
④ Real pearls have a smooth and cool feeling through hand feel, while fake pearls are often warm and greasy.
⑤ With a magnifying glass of 10 times, the growth texture can be seen on the surface of real pearls, but there is no growth texture on fake pearls, only the coating can be seen.
You can also rub two pearls against each other. If pearl powder can be ground and cleaned, the pearl is still smooth, so it is a real pearl.
I think you can find good things in border countries, but you must carefully identify them and bargain before you buy them.