Earrings are cut and sanded, for smoothness from the 2 tins in the images. The Blue tin is a gorgeous, luminous Sapphire Gin Box. The center piece is riveted to the circle with a brass rivet. 
Ear wires are gunmetal-plated brass, 15mm fishhook with open loop, 21 gauge.  Each pair come with silicone clear earring backs. 
Earrings have been treated with a museum grade wax to protect and enhance, called Renaissance.
Some Tins are Vintage and worn and add a Unique element to the Design.