I've never seen one like this, so romantic and beautiful.
You have the key to my heart
The key stem enamelled with FIDELITIE and the bit of the key set with a ruby to form a heart. The bit of the key, and the bow (the circle at the top) are edged with natural seed pearls. The bow contains woven hair under glass from the beloved.
This would have been a love token, an amatory piece.
 
weighs - 4.1g
50mm long
French circa 1780
Ruby heart 6mm tall
In excellent condition