in AM, also use 美国英语亦用 semiprecious
ADJ [usually ADJ n] (宝石)半珍贵的,次贵重的,半宝石的 Semi-precious stones are stones such as turquoises and amethysts that are used in jewellery but are less valuable than precious stones such as diamonds and rubies.
(宝石)半珍贵的,次贵重的,半宝石的