To adorn with jewels.
A precious stone.
A precious stone; gem; anything precious.
My husband was the apple of her eye, the jewel on her bosom. – The Home and the World by Rabindranath Tagore
But the setting was not the jewel. – The Marquis of Lossie by George MacDonald
Where could the jewel be? – Two Little Women on a Holiday by Carolyn Wells