demantoid
/dɪˈmæntɔɪd/
noun
- A bright green gemstone, a type of garnet, that is highly valued for its brilliance and fire.
- The jeweler showed us a stunning ring with a demantoid at its center.
- Demantoid is one of the rarest and most expensive garnets in the world.
- She collected gemstones and was especially proud of her small demantoid.