Hello, and nice find. I'm taking a bit of a guess here but I think it could be a pin-back brooch, and I have a couple odd twists on that. I think your photo shows the back of the piece with the hinged end of the pin toward the top of the frame. The clip or hook side of the pin would be toward the bottom as it is shown in your image, and I believe the hook might be missing or broken (possibly how it was lost) . I think the perforations could have served as attachment points, many of these had tintype or calotype (with celluloid cover) photographs. Now for some far out guesswork - and I could be way off on this - You mentioned that it was of really good quality - and looking at the wide slots cut in the back I think it might be a mourning brooch- the wide slits could have been used for tying or braiding some hair of the deceased loved one (a pretty popular thing in later Victorian times). Google mourning brooch or vintage pin back brooch and look through the images and you'll see some similar images. Like I said, it's just some ideas to research - hardly definitive. Cool find and thanks for sharing.