The biggest feature of sapphire is that the color is uneven, and the flat ribbons and growth lines with different depths can be seen in parallel hexagonal cylinders. Polycrystalline twin crystal development, common blinds double crystal grain. The cracking is mostly split along the double crystal plane, and the dichroism is strong.
sapphire
In addition to the above-mentioned common features, sapphire from different regions of the world has its own characteristics. In the 1980s, many sapphire deposits were discovered in the basalt along the eastern coast of China.
First, 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.
Second, look at the gemstone under natural daylight and artificial light source. The gemstone will look lighter under strong light, but it will be darker under normal daylight.
Third, to see if the color is uniform, cracks will affect the beauty and durability of the gem. If the plume stretches to the surface of the stone, a sudden impact will cause the stone to rupture.
Fourth, like rubies, be careful with imitations and a few fake pieces.
The color of the flash can be judged as the spinel or zoisite. The high hardness, high density and high refractive index of sapphire can be correctly distinguished from tourmaline and similar minerals by their respective mineral crystal characteristics. The gem-quality blue cone mine has only one origin in the United States, and the output is small. Although the color is similar to that of 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 Refraction and spinel are single refraction, such as the presence of red cordierite and zoisite in blue gemstones.
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