Hello, Peterb
The white one is made of tridacna, a type of organic gem.
In Buddhism, it is considered the seven treasures, the other six being: gold, silver, lapis, agate, coral and pearl.
In China, people believe that wearing accessories made of tridacna can bring good luck to career and love.
This one originally came from the South Sea, and was a gift for me about one year ago.
Diameter: 4 cm
Weight: 42 g
I showed it to my friends and one of them called it: the tear of the sea. I think it pretty good.
