Definitions

1. adjective

Resembling or having the appearance of a diamond, often used to describe a type of gemstone, such as a benitoite or a charoite.

“The diamantoid benitoite crystal was a rare and valuable find for the geologist.”

2. noun

A gemstone or mineral that has a diamond-like appearance or structure.

“The diamantoid mineral was discovered in the depths of the mine.”