diamantine

adj

1. Consisting of or resembling diamond.

   “[…]the Mine-men having little Iron-hooks, with which they fetch out the Diamantin-oar:[…].”

   “[…]Day after day he pierced the dark abyss, / Till he had reach’d its diamantine floor.”

   “It beats the mischief what fools we men will sometimes make of ourselves when a petticoat of the latest style, or a face of the dear old style—when women could smile honestly and sweetly, when their hands trembled without any diamantine rings—happens to enthrall us, and makes us feel as though we forgave the fellow that got the best of us in to-day’s business transactions.”

   “[…]capable to break through any protective shield of bronze or of diamantine walls:[…].”

2. (obsolete)Hard as diamond, adamantine.