Featured Antique French brooch French 19th century?

I think it is too thick to be enamel, ist could be a piece of colored glass or there is a Blue colored enamel at the bottom with a clear piece of glass (maybe also rock crystal) on top

 

It looks like it is blue all the way through, so I think blue glass.

 

There may have been a mark on the now missing bail. Surprised nothing on the C clasp.

 

I have discovered 2 tiny hallmarks in each side of the old clasp. Too tiny to see what it is and my camera is not good enough. Also a hallmark on the base of the old hinge but can't see in photo. Also 4 small marks on main body that could be a hallmark. A hallmark on the base of the soldering of new pin and a hallmark on new pin. I have realized the ding on the brooch is on the other side of the chip on the blue material. I'm thinking a negligent jeweler damage the brooch holding it to put the new pin. One of the hallmarks look like an A.

 

Someone pointed out the blue material looks like Georgian Royal Blue Bristol glass.

 

Yes cabochon rubies. It looked like in the photo there were 3 missing diamonds but it's a photo glitch. I checked carefully with my naked eye and none are missing. Don't think there is corrosion. Could be the photo quality. There are 2 different gold tones, gold and rose gold in the rings.

I have been thinking maybe it was a locket and the hinge and swinging clasp were to keep the back shut.

 

Maybe. But I look at a lot of antique brooches & pendants & have never seen a locket/memento compartment that latched that way.

 

Or it got damaged when it fell off because the old clasp wasn't secure enough & owner took it to jeweller to have something more reliable attached. Jeweller couldn't remove more of the original findings without doing damage, so, since the brooch fortunately is round, the new fittings were added in a new place.