In addition to the stone, the color-changing gemstones similar in nature to the stone are mainly spinel, garnet, sapphire, etc., and the andalusite is similar to the stone because of its strong pleochroism.
The difference between the stone and the spinel and the garnet is that the latter two are not polarized and pleochroic, and the stone changes in different directions, the different directions of the stone can also be different under the same light source. colour.
The difference between the changed stone and the discolored sapphire and the red column gemstone is that the discoloration effect is different, and the refractive index is also significantly different. Sapphire is blue-violet during the day and red at night, and the lowest value of the refractive index is greater than the maximum value of the stone. "Discoloration" occurs under the same light source and has a low refractive index (1.62).
The distinction between natural stone and synthetic color-changing gemstone
Synthetic color-changing gemstones mainly include synthetic marbles, synthetic sapphires and synthetic spinels. The difference between synthetic stone and natural stone is the common arc growth pattern and flux inclusion in synthetic stone. The two also have obvious differences in infrared light.
The difference between natural marble and synthetic stone sapphire is that the color change effect is significantly different. Synthetic sapphire is not green but blue in the daytime, but not red but purple blue in the evening. Synthetic sapphire sometimes also shows curved growth bands under magnification conditions.
The difference between synthetic spinel and metamorphism is that the synthetic spinel has no dichroism and the refractive index is slightly lower than that of the stone.
Identify key color-changing effects, inclusions, refractive index, and infrared spectra. The factors affecting the price of the stone are mainly the color change effect, size, transparency and enthalpy of the stone. In general, the more obvious the effect of discoloration, such as emerald green during the day and bright red at night, the higher the price. However, under normal circumstances, there are very few gemstones with such obvious discoloration effect, generally dark green during the day and reddish brown at night, that is, like a green tourmaline during the day and a pomegranate red at night.
In the size of the stone, the large particles have fewer marbles and are therefore more expensive. Generally speaking, the marble with large grain size, high transparency and little reduction has a high price. The price of high quality stone in the world can reach 1000-5000 US dollars per carat. Generally, the evaluation of gold emeralds is also based on factors such as the beauty of the color, the size of the grain, and the number of defects.
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