Lot (4) antique Czech 2 part tin mounted silver hand painted black glass cabochon buttons

Lot (4) antique Czech 2 part tin mounted glass cabochon buttons. With tin metal mounts and inset black glass cabochons with silver hand painted detail. The metal mounts on these buttons were plated and this inevitably wears off or oxidises with age. All have signs of this wear.
Origin: Northern Bohemia circa 1900's
Size: 14mm; 9/16" approx 
Material: Glass. Metal
Shank: Metal loop