Disk: 3/4" (19mm)
Total drop from ear: 1-1/2"
Enameling is fusing glass to metal, in this case copper. Each piece is fired multiple times including the back.
Last picture is the same size in my hand to show scale but a different color.
If you have landed on this page outside of Etsy follow this link to get back to my shop: tekaandzoe.etsy.com