Hi Barry,
I have also noticed the color variation in the color of the outer edge surface of the Hard Rock Roulettes. I think this is just a result of production process. The color difference is more prominent on some chips than it is on others.
I don't believe this is two differnt styles of chips but rather a color difference in a batch of replacement chips ordered to keep the roulette game running because of "over harvesting".
Take care,
Jerry