Best suggestion I have is to look through the custom ceramic sets here and on CT, in addition to browsing the web sites of ceramic/plastic chip manufacturers/distributors for ideas (brpro, pokerchiplounge, PGI, GOCC, ABC, OWPS, Sun-Fly, GPI, Matsui, etc.). Even searching for ceramics on eBay or google images might bring up a large list for ideas.
Do you have the face artwork completed, or a rough idea of what it will be like? I've always thought that rolling edge designs that were related to the face design worked well.