precious stone 
noun
A highly attractive and valuable piece of mineral, used especially in jewellery; a gemstone: a dazzling inlay of precious stones...
- The range of geological subjects is wide: minerals, rocks, precious stones, and the means of working them.
- Traders in Livingstone have been urged to start dealing in gemstones to sell the precious stones to the many tourists who visit the tourist capital.
- Much of the jewellery is set with precious stones.