Does diamond have a non-metallic luster?

No, diamond does not have a non-metallic luster; it exhibits a brilliant, adamantine luster, which is often described as glassy or reflective. This unique luster results from its strong covalent bonding and crystal structure, allowing it to reflect light exceptionally well. Non-metallic luster typically refers to materials with a more subdued sheen, such as dull, pearly, or waxy surfaces, which do not apply to diamonds.