Dukedogsmom, since that site is selling rosary necklaces, I wouldn't take them to be a good source on whether or not it's okay since they profit from it being so.

That said, those necklaces on the site look similar to rosaries but they do not look exactly like one. I'm not sure what the protocol would be for that.

I have to say that the few times I've seen people wear rosaries as necklaces I've found it to just look really dumb as though they didn't understand what they were for.