Sterling Silver and Moonstone Collar Choker Necklace

I have spent hours looking for a necklace like this and so far have not found one. I believe it is not too old at all; rather modern. I am not even sure what it is called. The little silver ball folds under the moonstone to open/close it.
There are no marks other than "925."
The moonstone looks so much better in real life.

Any help would be greatly appreciated.

Thanks for looking.