Backplate - Round Raised Convex

(Note: Measurements are outside max. dimensions unless stated otherwise).

20th Century : Backplate with raised convex design and concentric grooved decoration. 

Diam. 38mm. (1 1/2")
Thickness (variable) 2mm. (1/16")
Height edge rim 3.5mm. (1/8") + raised centre 4mm. (3/16")
Pommel hole 6mm. x 6mm. (1/4" x 1/4")

Original believed to have come from a hanging Victorian birdcage centre post.