Generally speaking, black pearls can be divided into the following three types: 1. Natural black pearls are cultured by nuclear inoculation (in Hyriopsis cumingii, maybe in some kind of mother-of-pearl). This mother-shell lives in the coral reef waters of French Polynesia. 2. Rare brown to black seedless cultured pearls have more and more colors, including dyed black pearls, radiated pearls and the latest so-called "laser-treated" pearls. 3. Imitation pearls made of black shells. Some rare imitations are coated with a layer of black essence de orient film on the surface of the ball core, or made into beads with black shells to polish the pearl luster. Distinguish natural black pearls from cultured black pearls, colored black pearls and imitations. Careful observation of the luster of the coated pearls shows that the pearlescence of the coated pearls comes from the bottom of the polymer thin layer, while that of the untreated pearls comes from the top layer of the pearls. The abnormal reflection of the color on the top surface of the pearl can also be observed, which is also helpful for the detection of this kind of pearl. The color of this pearl is pink from the top and blue from the side; The black pearls treated in this way have purplish tops and green sides. The characteristics of high-quality pure black pearls include: 1 Pearl surface is particularly smooth; Pearls feel sticky; The overlapping lamella edges of nacre are hard to see, and sharp instruments and concave colorless covering layers can be seen. This can be said to be the law of the market: as long as a commodity has a good market, it will inevitably be copied. Black pearls are no exception. It is not difficult for us to see so-called "black pearls" in jewelers, but some merchants forget to add the word "dye" before "black". When you ask whether these black pearls are real, profiteers can brazenly answer: these are real cultured pearls. Yes, they are. But he wants to tell you that the beads have gone through the process of processing and dyeing, just like a jade seller wants to tell you whether the B and C products have been optimized. Of course it's not illegal. I'm telling you, it's not illegal in China. But in Tahiti, the main producing area of black pearls, if a businessman sells dyed pearls, his reward is imprisonment! There are several common methods for pearl dyeing: silver salt treatment-soaking pearls in nitrate and dilute ammonia solution, and then reducing them in strong light or hydrogen sulfide gas to make the color of pearls black; Ray irradiation-irradiating pearls with gamma rays from cobalt sources to make them black; Dyeing the pearl core-after the pearl core turns black, implant the pearl core into the pearl shell; After the pearl is formed, the black pearl core makes the translucent pearl layer look black. Coating-coating a thin layer of black glue on the pearl surface. The difference between dyed pearls is easy to distinguish, and it is not difficult to say it is difficult. With the observation of the eyes, you should know that it is very close. Color-Black pearls have different shades of light gray to black, and its beauty lies in the hue it looks like. You can see a slight rainbow-like flash changing constantly. No two pearls are exactly the same. If you see a string (or even several strings) of black pearls with uniform and dull colors and rich halos, it is almost certain to be dyed pearls. The color of dyed pearls is dim, and the black gathered in the holes and defects is dark. This is easy to observe under a magnifying glass of ten times. Shape-Is the black pearl you see particularly round? Is the thin black pearl particularly round? The value is also very high. Typical black pearls are oblate, pear-shaped, oval and irregular, and many of them have flaws or rings, so if the "super-value black pearls" you see are smooth and round, they are probably dyed. Size-The diameter of seawater pearls in China or Japan is usually less than 9 mm, while the diameter of black pearls is at least 8 to 9 mm, so it is less than. An 8mm round black pearl costs more than 1000 yuan, while a dyed pearl of the same size is only worth 1200 yuan. If you are lucky enough to buy a black pearl at a reasonable price, Jinji requires the merchant to indicate on the receipt that the color of the pearl is natural. If you want to buy an expensive black pearl, the above identification method is still not reliable. Consider taking it to a jewelry appraisal unit for an exact identification: ultraviolet fluorescence test-under ultraviolet irradiation, black pearls often fluoresce, ranging in color from bright red to coffee red, but most dyed pearls do not respond to ultraviolet rays or show dim green fluorescence. X-ray test-the film irradiated by X-ray can show the dyed pearls treated with silver salt, and a circle of pale white appears between the pearl layer and the pearl core of the dyed pearls, which proves its dyeing composition. X-ray fluorescence test-pearls will emit radiation with a specific wavelength under X-ray irradiation. By measuring the degree of wavelength with a spectrometer, the chemical composition and the existence of silver salt can be detected. Infrared photography test-shooting pearls with infrared film. The image of black pearl is light blue, while the image of dyed pearl treated with silver salt is yellow, or blue-green to yellow-green.

Lz bought it, but it doesn't look real.