These chips seem to have been debunked quite thoroughly by Gene.

See here http://www.thechipboard.com/archives/archives.pl/bid/322/page/1/md/read/id/1214827/sbj/ss-monte-carlo-in-chip-chat-not/

For some reason I had been a defender of the attribution, albeit very lightly. I like to make sure all my points are addressed before completely siding one way or another, and to me there were always lingering questions.

1) Who stamped them and why? When I bought mine many years ago, they were selling for $2 each. Who would go through all that trouble for a $2 chip?
2) Where is the order card for the green? Until I saw Jamison's scan I had only seen the green with the rubber stamped address on it. Of the two Mason cards we have for the monogram there are no dull green chips. Jamison's other chip looks orange, which is also missing from the order cards.

These are the two things which keep picking at the back of my mind.

In my database they are NOT Monte Carlo chips, but there is something in the "Notes" section.