# opal

/ˈoʊpəɫ/ (US) · /ˈəʊpəl/ (UK) · CEFR C2 · Noun

Source: https://englishreference.com/word/opal
Updated: 2026-08-15

## Definition

a precious stone that shows different colors when the light hits it. It is often used in jewelry like rings or necklaces.

For teachers: a hydrated amorphous form of silica, valued as a gemstone for its iridescent play of colors. The internal structure diffracts light, creating a characteristic shifting spectrum.

## Examples

- She wears a beautiful opal ring.
- The jeweler explained that the opal's value depends on the intensity and variety of colors visible in the stone.
- Unlike diamonds which rely on clarity, the opal is prized for its unique internal fire, where microscopic spheres of silica scatter light into a vivid rainbow of hues.

## Usage notes

- Uncountable when referring to the mineral or material; countable when referring to individual stones or varieties.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.