Probably the eyeballs of dead fish were first used to pretend to be pearls. Therefore, there is a widely circulated idiom "fish eyes are mixed with pearls". Fish is dull and harder than pearls, so it should be easy to identify.
The originator of imitating pearls by industrial means is the French who are famous for their romance. 15 ~ 16 century is the most powerful era in France, and the European princes and nobles headed by France regard pearls as the noblest. Therefore, some historians call Europe at that time the "Pearl Age". Due to the scarcity and preciousness of pearls, in 1656, a pearl imitation with fish scale powder on a hollow glass ball appeared in France at that time.
Since then, the imitation of pearls, in addition to replacing different raw materials, has been coated with paint similar to pearls, basically following the footsteps of Chinese people. The Japanese who monopolize the pearl world are also in the leading position in the world for a long time. During the period of 1909 ~ 19 19, the Japanese kept exploring the imitation of pearls. One is to use white scale powder extracted from hairtail as pigment, but the cost of extracting 1000g raw material is too high. After that, they used mica particles with nitrocellulose and mixed various solvents, which greatly reduced the cost. The operation technology has also been improved from manual to mechanical, so the output has been greatly improved and the varieties are increasing day by day.
The jewelry industry in Taiwan Province Province, China developed rapidly in 1970s and 1980s, about 1970, and some manufacturers began to imitate pearls. At first, it imitated the Japanese, and later it improved in technology and technology. For example, the drop-burning method of glass bead embryo produced in Japan was improved to grinding method, which not only improved the output but also ensured the quality. By the end of last century, imitation pearls in Taiwan Province Province had surpassed Japanese and occupied a leading position in the world. With the process of reform and opening up in Chinese mainland, many jewelers in Taiwan Province Province set up factories in Chinese mainland, and pearl imitation technology was introduced into Chinese mainland from Taiwan Province Province. At present, due to low wages, Chinese mainland's output far exceeds that of Taiwan Province Province. In recent years, the Japanese have also set up factories in Vietnam to produce imitation pearls. However, high-quality imitation pearls are still mainly produced in Taiwan Province Province and Japan.
At present, pearl imitations on the market are mostly made of glass, plastic, shells or shell powder, with mica particles and titanium dioxide or fish scale powder as the outer coating.
All imitations are not naturally formed by the secretion of pearl oyster. Therefore, it is impossible to have the physical and chemical characteristics of pearls. Can be identified by the following methods.
1. appears
Most imitations are produced industrially, so the appearance is extremely regular. Every one is exactly the same. Pearls are exactly the same. Pearls are difficult to be uniform, and they can only be identified by careful observation and comparison.
2. Density
Beads made of glass and plastic are less dense than pearls. A little experience can be measured by hand.
3. Friction test
This method is the most commonly used and reliable. Two pearls rub together, and the smooth and silent one is an imitation; The real thing rustles. The reason is that the outer coating of the imitation is too smooth. Some people are used to grinding pearls gently with their teeth, which can be distinguished from the sound and smoothness.
4. Jump comparison
The bouncing ability of a pearl is much stronger than its imitation.
Zoom in and check
By observing the pearl epidermis with high power microscope, we can see the structure similar to fingerprints. This is the structural feature of aragonite and calcite. Imitation epidermis does not have this feature, and the epidermis is mostly orange peel-like.
6. Refraction
The refractive index of pearls is 1.530 ~ 1.685, which is the refractive index of aragonite. The refractive index of imitation is completely different from this.