Meaning: A type of gemstone, often black or banded.

Part of speech: noun

Example: She wore an onyx ring.

Category: Mineralogy

Synonyms:

• gemstone
• stone

Meaning: A type of gemstone that displays a play of colors.

Part of speech: noun

Example: She wore an opal necklace.

Category: Mineralogy

Synonyms:

• gemstone
• stone

Meaning: Showing varying colors like an opal.

Part of speech: adjective

Example: The opalescent surface shimmered in the light.

Category: Mineralogy

Synonyms:

• iridescent
• shimmering