Third in the second row of precious stones on the high priest's breast-plate (Exodus 28:18). Yahalim, which some translate "onyx," others translate it as "jasper." There is no proof the diamond was then known. Its engraving is very difficult, and the large size of the stones on the high priest's breast-plate makes it not probable the diamond is meant. Shamir is the usual term. (See ADAMANT.)
These dictionary topics are from Fausset Bible Dictionary, 1949. Public Domain.
Fausset, Andrew R. "Entry for 'Diamond'". "Fausset Bible Dictionary".