Ewing made the chip sometime between 1966-70.
I was told there was a booth at Caesars where people could get books on gaming tips.
The chip was exchanged there.
There are 3 different versions. Same both sides. Two others with different obverse.

I also have one with Caesars Guide To Gaming NCV on one side and John's Tahoe Nugget $500 NCV on obverse. Has both a $ sign and NCV.