This is because corals feed on marine plankton, and only the sea areas with sufficient light, moderate salinity and high water temperature can gather plankton that corals like. Corals live a fixed life, they can't move freely like fish, so they can only grow in warm shallow waters that meet the above conditions.

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There are also red corals, but very few.

Most red corals grow on the seabed with a water depth of more than 30 meters and a water temperature below 20℃. High-quality red corals are mainly produced in the coastal areas from Japan to Taiwan Province Province and the Mediterranean coast. Tunisia, Algeria, Morocco, Sardinia and most Italian coastal areas produce the most ideal red coral.

There is a story in Greek mythology: It is said that a hero in Poerxiusi killed Medusa among the three gorgons, hung her head on a tree by the sea, and her blood flowed into the Mediterranean Sea and became a red coral. So the English word "coral" comes from the Greek coral name-"gorgon". Because of this, red coral is not only the internationally recognized "birthday stone in March", but also the "national stone" of Italy, Algeria and other countries, symbolizing calmness, courage and fearlessness.

There are obvious differences in the color of red coral from thick to light, so the popular colors in different countries and regions are different in different periods. In the United States, deep red coral was once considered as the most ideal species, but soon, light colors became popular and once came from behind. Europeans love roses, while Arabs love bright red for a long time. After thousands of years' observation and practice, China jade artisans have turned red corals with different textures and colors into "Guan Gong Lian" and "Candle Red", which have been passed down from mouth to mouth. These names full of folk colors have left a deep impression on every amateur. For example, the "oil-squeezing ghost" has thick branches, fine texture and high hardness, but it is too transparent and fragile. There are white pistils in the middle of the branches, so the quality is slightly poor. Another example is "children's noodles", with dense branchlets, colored stems and worms. The pistil of each branch leads to the trunk, and the two trunks sometimes grow together, but they grow easily, with cracks and obvious thin longitudinal lines on the whole. These red corals with different shades can only be used for low-grade jewelry and inlays. "Chili red", which is really called the best, has long been rare because of over-exploitation in past dynasties.

Red coral is not only beautiful in color, but also regarded as one of the "seven treasures" in Buddhist scriptures, which has the characteristics of ward off evil spirits and dignity. In the Qing Dynasty, red coral worshipping beads was a status symbol only enjoyed by first-and second-class officials, so the value of coral doubled, and it sold well to Tibet in addition to the Central Plains. It is said that the crown beads worn by the prince of Tibet in those days were the best corals. Other officials wear different levels of coral hats according to their positions, and wearing coral has become a national custom. During the Republic of China, there were several jewelry stores in Beijing, such as Quanxing, three sheng Xing and Hengshengxing, which were famous for their "Mongolian Tibetan Village", all of which proved the charm and value of red coral.

The preciousness of red coral led profiteers to take the opportunity to make fakes. At the latest, from the Republic of China, there was a pure chemical celluloid. Its feeder is glazed with coral, covered with lead, coated with coral paint and painted with texture, carved into round beads with cow bones or talc, and infiltrated with red. This is a fake coral for sale. Some of these fake methods have been passed down to this day, but it is not difficult to identify them: the "coral" made of materials contains bubbles inside, and the debris is shining, without real coral fingerprint patterns; The "coral" made of glass is conchoidal fracture, but the real coral gap is smooth; The "coral" made of noodles is not bright, and it has cracks after a long time, and the tapping sound is dull; Coral stained with bone keratin can be identified by wiping with acetone. Contemporary coral imitation uses advanced science and technology, such as white coral or sea bamboo similar to coral, and "synthetic coral" in gilson. It is extremely concealed. If we don't have rich experience or use scientific instruments to detect it, it's easy to confuse fish with pearls. In addition, the real red coral can be divided into the following three categories according to its commercial value: 1, dead coral, which has completely stopped growing, is seriously damaged and has many holes; 2. The inverted coral has basically stopped growing, and the damage degree is still small; 3. Living coral, which can continue to grow on the seabed, has a film on its surface, which is dazzling and exquisite after polishing, and is the most precious among red corals.