The evaluation and purchase factors of sapphire are color, weight, transparency and clarity. The biggest feature of sapphire is that the color is not uniform, the polycrystalline twin crystal is not developed, and the dichroism is strong.
1. The color of Sapphire is an indicator of its value. A very dark sapphire may only sell for one hundred dollar one card, but a good cornflower blue sapphire sells tens of thousands of dollars per card. In the United States and Europe, people prefer darker sapphire. In Hong Kong, consumers love medium-depth blue, and the color of this sapphire is higher. Put the Sapphire on your arm and carefully observe whether it is blue or black. If it's blue, then your choices are not too far away.
2. Look at gems under natural daylight and artificial light sources. Gemstones appear to be lighter in bright light, but darker in normal daylight.
3. See if the color is uniform and the crack will affect the beauty and durability of the stone. If the plume stretches to the surface of the stone, sudden impacts (such as when the sparrows are licking) can cause the gems to rupture.
4. Don't forget to observe the cut and proportion of the gemstone.
5. Like rubies, be careful with imitations and a few fake pieces.
Sapphire and similar minerals can be correctly distinguished by their respective mineral crystal characteristics. The gem-quality blue cone mine has only one place in the United States, and the output is small. Although the color is similar to that of the sapphire, its hardness is small, and the Mohs hardness is only 6-6.5, so the hardness can be distinguished from the sapphire alone; the natural sapphire has double The refraction and the spinel are single refraction. If a red flash can appear in the blue gemstone, the blue gemstone can be judged as spinel or zoisite; the high hardness, high density and high refractive index of the sapphire can be Tourmaline, cordierite, and zoisite are distinguished.
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