Marked RBM Atrice 1874 with a Bee.

There is also a patent number. 

It does not latch closed. 

It is not marked gold filled that I could find, however all of the RBM Atrice lockets from 1874 that look like this are gold filled and I do not see markings on those either. 

This does show wear and I am not sure if it's missing something that was originally inside. 

See photos for assessment. Selling as is for collectible value.