Heres a few possibilities:
Blum on 51st Street in BP, anywhere in Diamond Center, Olshwang, Feldmans Jewelry on 16th, Kaufman’s on 16th, Ebay from a Seller w a good rating and good return policy, …..
You might be able to get the same look if you buy a string of pearls and buy a diamond pendant to attach and then be able to use with a chain as well.