I need help identifying this NY Stcok Exhange commemorative

I picked this coin up at an auction and they didn’t know anything about it.  I have looked through all of my identification apps and even google searched my pic.  I found one on worthpoint that was played but weighed 26 grams.  This one is stamped ”sterling” on the rim and weighs 30.5 grams.  It also has the number 299 stamped on the rim.  The auction description for the plated one said that there were 300 minted, so I am wondering did they also mint 300 sterling coins as well? I would appreciate any help you could provide as well as possible value.  Thank you 

https://www.bullmarketgifts.com/1972-NYSE-Buttonwood-Agreement-Anniversary-Pendant-p/v1036-pendant.htm

Usually it will be mostly bronze, some silver plated, and even less silver or gold - so yours should have a lower mintage than the other two.

edit:

Didn't see the 299. I think your conclusion is correct.