Antique c.1770 French Portrait Miniature, Rare 18k Gold Frame w Heart Lock and Key

A superb portrait, but a slice far left has been broken and lost over the 250+ years since it was painted. I’ve seen these very old frames in museums, but this one is the only one I’ve ever owned. It’s a hinged locked, opening book-like, two perfect thin beveled glass panels protecting the painting and hand-written document on backside. The locket folds closed and 2 small rings align, held fast by the tiniest working lock in shape of a heart. Its tiny key hangs from one of 5 gold chains attached up top to the closed hanging loop. The frame is rare, isn’t perfect, consider it fragile, but what a treasure it truly is. And that we have almost the entire original portrait of a nobleman, some info in old French handwriting, most of which I’m unable to make out. Perhaps you can do better. Parchment, it appears to have once had a small wax seal affixed, though I can’t imagine the slender locket frame would close with a was seal in place. The frame is 1 7/8″ x 1 5/8″ and only 3/16th” in depth, closed. The panels of glass are very thin, yet neatly beveled, no chips.  That tiny heart lock is only 1/2″ long and the key is just 3/8″ in length. Delicate, and yet 250 years and all still together.  A handsome man, indeed. In his life, he saw much upheaval in France, Revolution, wars, The Terror, Napoleon come to power. You can see his hair is pulled back into a braid at nape of his neck. 

Good condition to very good for age and type. Delicate, I barely dare to hold it. Hinged all along one side, it opens like a tiny book. Held closed by the small working lock, its key dangling. The portrait is superb, but it has a slice missing to the left. The backing paper has been blackened to make it less noticeable, but of course I want you to review it. I’m unsure which is more valuable here, the antique frame (I’ve only seen them in museums) or the handsome Frenchman’s tiny painting in the pendant-like mount.