Besides the words El Cortez (and there are other El Cortezes), nothing about the chips indicates Vegas.

There is one on ebay now. I would like it as a crest & seal. However, I can't afford it as a Vegas chip (I might go $1800 but t will go much higher)

I'm not saying that I know where it is from. I do not. But I don't see the Vegas connection. I know if I brought it up today, Gene would ask for proof. What was the proof that makes everyone thionk it is Vegas.