a black contour marker for glass and porcelain. The tip is mm thick and the color is very opaque. Let your decorated porcelain dry for 4 hours and then be cured in the kitchen oven at for 90 minutes, to be dishwasher safe.
I can do this with the Sharpie idea. Sharpie design on mug, bowl, plate, or any other oven safe glass object! 350 degree oven for 30 min, and there you have it! Instant art to display your tea + coffee + yummy food in.