I. Classification of Causes According to the causes, pearls can be divided into two categories: natural pearls and cultured pearls.
1. Natural pearls: pearls formed by wild shellfish in the natural environment. Natural pearls can be formed in seawater, lakes, rivers and other environments suitable for growth. These pearls are very rare and expensive.
2. Cultured pearls: pearls are gradually formed in natural environment by artificially inserting pearl cores or foreign bodies into cultured pearl mussels and then culturing them. Nowadays, most of the pearl markets are cultured pearls. According to the characteristics of pearl core and foreign body, cultured pearls can be further divided into nucleated pearls, seedless pearls, regenerated pearls and shelled pearls.
(1) Cultivation of seedless pearls: insert a small section of the mantle of living Pinctada into the connective tissue of the protagonist Hyriopsis cumingii or other Pinctada, just like the entry of foreign bodies in natural Pinctada and mussels, thus producing seedless pearls that are basically the same as natural pearls.
(2) Cultivation of nucleated pearls: the prepared pearl cores are implanted into human shellfish and mussels to stimulate them to secrete nacre, and the pearl cores are wrapped layer by layer to form pearls.
(3) Regenerated pearls: Regenerated pearls refer to pearls formed by pricking a wound on the pearl sac, gently squeezing out the pearls, and then putting the pearl oyster farmers back into the water. After the wound healed, the epithelial cells of the pearl capsule continued to secrete nacre.
(4) Shelled pearl: It is a kind of hemispherical pearl cultured in human nucleus and combined with the shell of Pinctada. Bead cores are usually made of talc, wax and plastic.
2. Classification by origin 1. Dongzhu: This is a natural pearl from the Persian Gulf, which is one of the famous pearl producing areas. The color of mollusks that produce pearls is mainly white, milky white, with strong green pearl luster and particle size of.
2. Nanyang Pearl: Generally speaking, it refers to pearls produced in the South China Sea (including Myanmar, the Philippines and Australia). The mollusk that produces pearls is mainly Rctada maxima. Pearl is characterized by large particles, round shape, thick pearl quality, white color and strong pearl luster, which is a treasure among pearls.
3. Japanese pearls: Japanese mariculture. The mollusk that produces pearls is mainly Rntada funcata, and now it is also produced in South Korea, China and Sri Lanka. Pearls are round and white, and the common size is 2 ~10 mm.
4. Tahiti pearls: mainly produced in Tahiti, French Polynesia near the equator. The mollusks that produce pearls are pearl mussels and pearl mussels. Pearls are naturally black with green, excellent luster and metallic luster. This variety is more precious.
5. Pipa Pearl: It is a freshwater pearl cultivated in Lake Biwa, Japan. The mollusk that produces pearls is schlegel mussel I, which is characterized by oval shape and smooth surface, and is a fine product of freshwater pearl cultivation.
6. Nanzhu or Hepu Pearl: It is a kind of seawater pearl, produced in Hepu, Guangxi, China. Molluscs that produce pearls include Ma Bei and Pinctada maxima. Due to the good production environment of pearls, pearls are of excellent quality, round shape and strong luster, which is the best in the world.
7. Zhu Bei: It is a freshwater pearl, which is produced in Mudanjiang, Heilongjiang, Yalu and Wusuli rivers in northern China. As early as 2000 years ago in the Han Dynasty, it was recorded that the quality of pearls was superior to other freshwater lakes. After the end of the Ming Dynasty, due to over-exploitation, resources were eradicated. In the Qing Dynasty, the crown, robes and other ornaments in the royal family were decorated with North Pearl, which was also called "East Pearl" at that time.
8. Pearl in Taihu Lake: Taihu Lake is one of the important bases for freshwater pearl culture in Jiangsu and Zhejiang provinces of China. The mollusks that produce pearls are mainly mussels, especially pearls cultured with Hyriopsis cumingii, which are characterized by few surface wrinkles, roundness and softness, and bright luster. In addition to the above-mentioned producing areas, freshwater pearls in China are also found in Anhui, Hunan, Hubei, Jiangxi and Sichuan.
9. Zhu Xi: In a broad sense, it refers to pearls produced in the Atlantic Ocean, and in a narrow sense, it refers to pearls produced in Italian waters, mainly seawater pearls. Due to the deterioration of local water quality, Zhu Xi's output is getting less and less.
3. Classification according to production environment 1. Seawater pearls refer to pearls produced by seawater shellfish, which can be further divided into natural seawater pearls and cultured seawater pearls according to their causes. The quality of seawater pearls is generally higher than that of freshwater pearls.
2. Freshwater pearls refer to pearls produced by freshwater mussels, which are generally produced in various lakes, rivers and streams. China is the main producer of freshwater pearls, accounting for 85% of the international freshwater pearls, followed by Japan and the United States.
4. Classification of Pinctada 1. Pinctada martensii: It is produced in Pinctada martensii, and 90% cultured pearls in seawater belong to this type. This kind of pearl is the most common cultured pearl on the market. Akoya pearls are seawater pearls produced in Malpighia. Akoya is a transliteration of Japanese, which means Malpighia.
2. White butterfly pearl: It is produced in the body of white butterfly and is another kind of pearl cultured in seawater.
3. Penguin pearls: Penguin pearls are also seawater pearls. This kind of pearl has large particles and good quality, but its output is low.
4. Hyriopsis cumingii pearl: produced in Hyriopsis cumingii, it is the main variety of freshwater cultured pearls, accounting for more than 95% of the market.
5. Folded mussel pearls: similar to Hyriopsis cumingii pearls. Because of its fast growth rate, pearlite wrinkling, poor quality and low output.
6. Black butterfly pearls: produced in black butterflies, more than 90% are produced in Tahiti, and the colors are black, gray, blue, green and brown.
7. Conch Pearl: pink conch that lives in the Caribbean. Beads are usually pink with white or brown in the middle. They have unique flame-like surface marks. High-quality shapes are usually oval with symmetrical sides. Arabs and Europeans have a soft spot for this.
8. Abalone pearls: The pearls produced by abalone are colorful, just like the discoloration of opal. They have different shapes, which are a combination of green, blue, pink and yellow. Abalone pearls with high quality are of great value, mainly produced in New Zealand, the United States, Mexico, Japan and South Korea.
9. Australian vein beads: produced in nautilus, belonging to cephalopods in mollusks. This kind of beads, like horse nose beads, are filled with glass in the middle and added with a layer at the bottom, which is cheaper and often used in earrings, pendants and other accessories.
5. Other classifications 1. Classification by color: pearls can be divided into white pearls, black pearls, pink pearls, golden pearls, purple pearls, yellow pearls, variegated pearls and dyed pearls.
2. Classification by morphology: According to the shape of pearls, they can be divided into round pearls, oval pearls, flat pearls and irregular pearls.
3. Classification by size: According to the size of pearls, it can be divided into: pear bamboo: pearl beads with a diameter less than 5 mm; pearl beads with a diameter of 5-5.5 mm; pearl beads with a diameter of 5.5-7 mm; pearl extra-large pearls with a diameter of 7-7.5 mm; pearl extra-large pearls with a diameter of 7.8-8.0 mm; pearls with a diameter of more than 8 mm.