We know that Dow filter is a kind of filter, which only allows red light and orange light to pass through. Dyes used for jadeite dyeing usually contain chromium salts. It will emit red light when its concentration is high, and it will appear red under Dow filter. However, if the dyed color is not deep, the concentration of chromium salt is not high, and it is red under Dow filter, which is not easy to observe. In addition, natural green jadeite sometimes contains a small amount of substances that emit red light. When observing green jadeite with Dow color filter, it needs to be carefully analyzed, which will be indicative and cannot make a conclusive judgment.
So what's the difference between natural green and dyed green of jadeite? We already know the reason why jadeite is dyed. The reason why natural jadeite has three colors of green, white and purple is because the particles that make up jadeite have three colors of green, white and purple. Therefore, when we look at the color of a natural jadeite, its color and crystal are inseparable, while the original crystal of dyed jadeite is colorless. The dye that enters jadeite through impregnation permeates along the intergranular cracks or some tiny cracks of the crystal, so there is an obvious boundary between color and crystal. 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 the "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:
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.
(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 the attractive appearance of "fire" light. 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. Natural gemstones have "ten Hong Jiu cracks", 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. 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.
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.