As the pearl is also lifespan, yellowing is the manifestation of the aging of pearls.
The pearl is by mussel conceived, its luster and beads have a certain life. Although the life span is longer than the human, but the exposure to the air for a long time, the nacre layer is oxidized, from white to yellow. In the long term, the pearl layer will chap and eventually become a pile of residue.
Scientific research indicates that pearls are calcium carbonate crystals separated from the special colloids of shellfish. Each pearl contains more than 90% calcium carbonate and about 4% of the water. The pearl is brightly lit by the water. The long, non - used pearls tend to run off water and turn yellow after about sixty or seventy years or more to one hundred years.
The aging level of Pearl and keep proper, such as in the Qianlong cap, there was a big pearl, from generation to generation to the last emperor of the hand, the experience of more than 200 years, until now still very good