Like the diamond in hardness or luster.

Pertaining to luster. Transparent minerals with a very high luster are said to have an adamantine luster.

a brilliant type of luster, like that of a diamond.

not capable of being swayed or diverted from a course; unsusceptible to persuasion; "he is adamant in his refusal to change his mind"; "Cynthia was inexorable; she would have none of him"- W.Churchill; "an intransigent conservative opposed to every liberal tendancy"

unyielding; inflexible; pertinacious

According to a reply in a NAWCC bulletin, Adamantine is a veneer made from celluloid made up of cellulose (cotton), nitric acid and Camphor. The paper thin veneer is highly flammable and is very vulnerable to heat, including sunlight. The material is very tough. To clean it, Seth Thomas originally suggested just using rag with 'sweet oil' on it (Sweet oil is a vegetable oil similar to Olive Oil). Do not use ANY acids or abrasive polishes on this material.

Adamantine is a mineral, often referred to as adamantine spar. It is a silky brown form of corundum. It has a Mohs rating of 9.

Made of adamant, or having the qualities of adamant; incapable of being broken, dissolved, or penetrated; as, adamantine bonds or chains.