This arrived in the mail today. It is breathtaking. It is a vintage Japanese glass cabochon, with 2 tiny birds perched on flowering branches, all handpainted with incredible detail. It is quite dirty. I used a cotton swab dampened with water to clean around the paint, but after working with it, my guess is that the paint is pretty robust, so I'll clean a bit more agressively in the next pass.
The backs of these cabochons were originally foiled in red, green and yellow, so the colors would have shown behind the birds like a glowing rainbow. You can catch glimpses of that in this cabochon, but the foil is seriously damaged and is easily removed. The glass is frosted, so I think that if the foil is removed, the cabochon will still be quite beautiful, just a bit different from how it was originally intended to look.
One of the features of this cabochon that leaves me awestruck is the size. This cab is about 17mm or 5/8 inch long. The only word I seem to be able to come up with to describe the degree of detail, artistry and craftsmanship is "breathtaking".