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. The most accurate and reliable way to identify genuine and fake diamonds is to measure the thermal conductivity data with a "thermal conductivity meter", but the "thermal conductivity meter" is expensive.
Because diamonds are noble and luxurious ornaments, it is not uncommon to substitute or pass off diamonds with cheap gems, artificial gem and even glass in the market. 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.