How do you know if the black pearl is dyed? Why are black pearls so expensive?

How do you know if the black pearl is dyed? 1. Ultraviolet Fluorescence Test The fluorescence of black pearls under ultraviolet light ranges from bright red to coffee red, while dyed pearls emit light green fluorescence.

2.X-ray fluorescence test pearls will emit radiation with a specific wavelength when they are irradiated by X-rays. Measure the wavelength with a spectrometer to determine whether there are chemical components and silver salts in pearls, so as to determine whether pearls are dyed.

3. When shooting pearls with infrared film, you can see that the image of black pearls is light blue, while the image of pearls dyed with silver salt is yellow or green-blue to yellow-green.

4. The color of pearl core The color of natural black pearl is white, while the color of irradiated black pearl core is black. Therefore, it can be preliminarily judged whether the pearl changes color after irradiation by the color of the pearl core, but this identification method is destructive to the pearl.

5. Long-wave ultraviolet test Black pearls show dark reddish brown to bright red fluorescence under long-wave ultraviolet irradiation, but the irradiated pearls will show moderate to weak yellow-green fluorescence or extremely weak blue fluorescence under long-wave ultraviolet irradiation. Ultraviolet rays. White fluorescence.

Why are black pearls so expensive? Black pearls have strict requirements on the growth environment and must grow in natural and pollution-free waters, so the output is also very rare. There are two producing areas. One is Tahiti in Polynesia, where 95% of the world's black pearls are produced. The other is Penglin Island and Majushiki Island in Cook Islands, accounting for 4% of the total output. These two areas live together in the south-central Pacific Ocean, so the black pearl is also called the black south pearl.

Even in the case of artificial breeding, the probability of breeding black pearls is very small, so the annual output of black pearls is estimated not to exceed 6.5438+0.5 million. The particle size of most black pearls is between 9mm- 10mm, and the particle size of more than 60% black pearls is less than11mm.

How are black pearls made? Dyeing pearls: soak light-colored pearls in nitric acid solution and ammonia water, then take them out, and irradiate them with sunlight or smoke them with hydrogen sulfide to make them gray-black. Radiation will discolor pearls. Light-colored pearls can be irradiated with R rays to darken the eyes. However, the pearls that can blacken are limited to freshwater pearls containing trace manganese and the inner nacre of freshwater mussels. Natural pearls grown in seawater and mother-of-pearl grown on the outer layer of nucleated cultured mother-of-pearl will not change color. How is the black pearl formed _ Is the pearl white or black?