ONYX

Semi-precious stone used in making cameos (4)

Solution has appeared in 4 crosswords (3 across and 1 down):

• Quick crossword No 16,689 — 2023-11-01 00:00:25
  7A: Semi-precious variety of agate (4)
• Quick crossword No 16,377 — 2022-11-02 00:00:46
  22A: Variety of agate with different colours in layers (4)
• Quick crossword No 15,631 — 2020-06-11 23:00:05
  5D: Kind of agate (4)
• Quick crossword No 15,420 — 2019-10-08 23:00:36
  23A: Semi-precious stone used in making cameos (4)