I think what you're seeing, Chuck, is a moire pattern formed by the pink-dot pattern in the printing screen and the transparent pebbled pattern of the chip surface. You see the same thing over a larger area in the Caesars Tahoe $1 gold chip. It varies from chip to chip depending on how the dots and the pebbles happen to line up. I wouldn't say it's a variety, just a different appearance from chip to chip based on the manufacturing method.

DonL