TCR lists three for Horseshoe-mold dollars from Binions. It would be interesting to see a scan of all three that you think represent the three varieties.

There is a grey chip scanned on on The Chip Guide but only by itself. Since scanning adjustments can greatly affect the perceived color, a single scan of the three or side-by-side inspection of all three is the only way to really tell.

The brass dust in the chips certainly does turn green with age, oil from the skin, and air pollution. It can affect the color on used chips, as you say.

Who has all three to show in a single scan as my scan did? Maybe TCR authors have one in their files?