Found this mystery "diamond ball" or charm... anyone know what it is?

We bought this home from a little old widowed lady, and she left a bunch of stuff behind, like an old oil painting from the early 1900's. Her fridge, washer and dryer, and etc, and our contract states that we get everything in the home AS IS. So, the home is now ours, as are the problems we're having like finding out there are rocks in our plumbing (of all things!) from some work that city workers did. We have no water and are supposed to move in this weekend... ahhhhh! Anyway, so we are already spending money on having plumbers come and figure out all this stuff that is not fun.

WELL, Long story short, I was at the home, and had ripped up the carpet to get to the hard wood floors because I'm going to surprise my wife and refinish them. I was scooting a carpet across the floor, lying down with my hammer and flat-head screwdriver, and prying off the carpet strips along the base of the walls. This Master BR has a door in it that leads to the outside, because this used to be a rec area that migrated to a large Master BR. The door is sealed shut and the carpet pad and carpet itself covered the inch of space between the floor and door bottom easily.

So, the carpet was pulled up and I had finished the entire room, except for the closet. Inside the closet, is the sealed door that use to lead to the outside. Deep under the sealed door I saw something shiney, and thought, "Hmmm, what was that?" I grabbed the longest nail I could find and fished it out, and was immediately cautiously excited. Yes, something glimmery caught my eye, and at first I was super excited that I'd found diamonds. It looks old.

I'd found a ball piece pendant of sorts with 12 nice size diamonds... again, it appears be a pendant for a something, or used to be part of an earring. It's basically a little oblong shaped ball, crusted with diamonds set in (not glued). It has 12 "diamonds" in it, but we have no idea if they are real. The little old lady who lived here was 87 years old and they apparently carpeted the place 30 years ago, so the piece has been sitting lodged under that door for who knows how long? Probably at least 30 years, maybe more. In the pictures, I'm holding the little "loop" that connected this charm to whatever it was used for... a bracelet? An earring?

I carefully pried one of the prongs open, and was saddened that the back of the "diamond" had a goldish/bronzish coating of some kind on the back of it. I was saddened and a little bummed, and said to my self, "Dangit, costume jewelry..."

However, for hoots and hollers, I started researching to learn if any diamonds do in fact have foil-like lay on the backs of diamonds, and apparently this was common practice in Georgian and Victorian times, so now I'm getting a little excited again and wondering if anyone can help. This little old lady has tons of friends and family who had been coming to visit her in her home from Poland, for large family get-togethers, for years and years. It was an annual summer thing. They'd have 10 and more people sleep in the extra long 1 car garage in tents and with sleeping bags, many more sleeping in the house, and I'm told the family members looked more forward to these events than anything else in their lives. They are a long, connected group and family of Poles, and some of their parents came over on the original boats to Ellis Island in the late 1800's and early 1900's.

All of this together has my mind going a little and wondering if there is any chance we have anything here. It looks very similar to some of the Georgian diamond stuff I've been researching online. It could also be Victoria style, I just have no idea. I do plan to take it to a local jeweler tomorrow to learn if it is diamond or not. But in the meantime, wanted to share it here and see if I could get any opinions and insights as to what you think it might be. Your help and ideas are certainly appreciated! Thank you!