Symbolism of Locket with Iron Cross and Garter

I picked up this locket this weekend. It's the second locket I've found with a Maltese/Iron Cross, but what makes this one unique is that it also has a garter/belt from which the cross hangs. I was wondering if I could get your thoughts on its age (earlier than WWI?) and perhaps the symbolism associated with the piece. Is it a mourning locket as I suspect?

It still has both its glass panes. At least I think they're glass. They feel almost like mica to me and have a yellowish cast; their edges are sharp enough that I think I actually got a small paper-cut from one.

As far as value goes, do you think there's any interest in these sorts of things? I've always found objects related to the civilian side of war more interesting than militaria itself, but maybe that's just me.

 

I think your locket is early 20th century. I also think there could be an iron cross reference. The iron cross was instituted in 1813, so long before this locket was made.
Maybe a relative or sweetheart of a bearer of the iron cross wore this with his photo and a lock of hair inside?
If the German tradition is anything like the Dutch tradition, this was probably not a mourning locket. The Dutch used to wear silver for mourning, gold was considered to happy a colour, ostentatious during mourning.

Although this is not miltaria per se, maybe @kristiaan has an idea about this?