The insert is 6.7 cm diameter and has different grape varieties.  The background is made to look crazed  and vintage

Diameter across coasters is 10 cm

There is a small hanging hole on the back if you chose to display these pieces

There is no wording on the back, but there is a backstamp imprint of a angle.  

I believe this is Zierteller pewter, but they may possible be another brand.