1) a precious stone (known for its hardness)

1a) perhaps the jasper, onyx, or diamond

Root √הלם: הָלַם vb strike hammer strike down .

יַהֲלֹם הלם n.[m.] jasper onyx smite hammer Ex 28:18 39:11 Ez 28:13 a precious stone,? (so 𝔊, 𝔙), or? (appar. fr. √; owing to its hardness, as able to,?)—mentioned in lists of precious stones.