very hard native crystalline carbon valued as a gem
source: WordNet 3.0
A stone imagined by some to be of impenetrable hardness; a name given to the diamond and other substances of extreme hardness; but in modern mineralogy it has no technical signification. It is now a rhetorical or poetical name for the embodiment of impenetrable hardness.
source: Webster 1913
adjective satellite
impervious to pleas, persuasion, requests, reason
He is adamant in his refusal to change his mind. Cynthia was inexorable; she would have none of him. An intransigent conservative opposed to every liberal tendency.
