Gem
Definition 1 of 4
Pro Tip 1/2
Jewelry Context
Use 'gem' for stones in rings, necklaces, and other fine jewelry. He gave her a ring with a shining gem at its center.
Pro Tip 2/2
Figurative Use
'Gem' can describe something cherished or valuable, not just stones. This old book is a gem; it's rare and precious to me.