These decorative buttons are made by a small Portuguese manufactory that is able to coat wood with a ceramic layer.
The present button was made of coconut wood, is 15mm wide and has two drilled holes. The ceramic glaze is shiny and runs all over the place.
These colours are currently available:
Puder (Light Pink)
Senf (Mustard Yellow)
Olivia (Olive Green)
Note: The buttons are washing machine safe.