I tried to do some research on these chips a while ago, and posted what I could put together in the California ChipGuide.

Thought to have been used at the Five Brothers Bar and Card Room in Lower Lake, California in the 1980s. The chips look to me to be much older than that. Armin Pfaender notes in his guide that they were first bought earlier by Jim Ross (sometimes called Diamond Jim). I haven't been able to find anything about him in old newspaper archives.

Does anyone know anything about Jim Ross or more about these chips?