"Let's assume I got the chip with no history to it. What would you make of it?"

I would call it a UFC same as I am doing now.
Except if I had it, I would start digging.

"If, as I was told, the chip is an adverstising chip (she wasn't sure), there's a very good chance that workers(dealers), having had little reason to come in contact with it, would not remember such a chip"

I never said they would. Most old timers can not even ID the chips they dealt the games with.

Advertising chip? For a casino that closed their games every time a grand jury conviened? I find this part of her story very questionable.

Made in the 30's? Is it a USPC chip?