2. Thermal conductivity detection: set the thermal conductivity meter to 4 grids to detect gems. Rock crystals can rise to 2 grids of yellow, and when the area is large, they will rise to 1 grid of yellow, while pseudocrystals will not rise.
3. According to the handle, crystals are all crystals, which have fast heat transfer, while glass is amorphous and slow heat transfer. Therefore, holding the crystal will make you feel cold, and after wearing it for a short time, it will synchronize with your body temperature; And glass has a sense of temperature.
4. Hardness measurement: The hardness of rock crystal is 7, while the hardness of glass is only 5. So when testing, anything with hardness greater than 5 may scratch the glass.
5, look at the price, a penny for a penny, even rock crystal is divided into multiple grades, the price is also a world of difference. There are not many natural topaz with good quality, so don't expect to buy 3A topaz with cheap money. The better the crystal, the more expensive it is.
6, hair identification (birefringence), specifically for the hair identification of spherical crystals: put the crystal on a hair, gently turn the spar, when turning to a certain direction, double shadow appears, that is, one hair becomes two, the effect is clear and obvious, this is the birefringence phenomenon caused by the crystal arrangement of rock crystals, and fake crystals can't do it.
The more obvious the double shadow effect, the better the crystal quality. Some rock crystals with too many impurities may not be double-folded, or their hair will be twisted and straight lines will be broken, so the quality of the crystals is even worse.
7. Optical identification shows that the glass is an amorphous isotropic body, and the crystal is an anisotropic body. It rotates 360 degrees under a polarizer and looks different in light and shade. It is a rock crystal, but it is a pseudocrystal. In addition, some rock crystals, such as amethyst, have dichroism, while pseudocrystals do not.
8. According to the observation of inclusions, most synthetic crystals are pure inside, so large that they look perfect; Crystals generally have "defects" such as cotton and cracks. Natural products are pure, but rare, and things are rare, which is reflected in the price. The natural products of topaz with the same color clarity are much larger than synthetic crystals.
Extended data:
shopping tips
1. Look at material selection: crystal products with excellent material selection should not have star-shaped, cloud-like or flocculent gas-liquid inclusions. It is best to be pure, smooth and crystal clear. If cracks and spots of different shades are found, they are defective.
2. Look at the workmanship: there are two kinds of processing techniques for crystal products, namely grinding and carving. Such as crystal necklaces, bracelets, earrings, etc. Belonging to abrasive products; Guanyin statue, painted snuff bottle, etc. It belongs to sculpture. A well-made crystal product should be exquisite, which can fully show the external beauty (shape, style, symmetry, etc. ) crystal products, but also to maximize its inner beauty (crystal clear, smart color).
3. Look at polishing: the quality of polishing directly affects the value of crystal products. The crystal must be polished with emery during processing, and rough production will make the crystal surface have friction marks. Good crystal products have good natural transparency and luster, which is "burning with fire" in the local dialect.
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