also: ペリドート
noun
peridot
A green gemstone, the gem-quality variety of olivine. Used in jewelry and as the August birthstone.
彼女はペリドットの指輪をはめている。
She is wearing a peridot ring.
ペリドットは８月の誕生石です。
Peridot is the birthstone for August.
Olivine is the mineral name; peridot specifically refers to the gem-quality transparent green variety.
Borrowed from English 'peridot', ultimately from French 'péridot'.