Some old shades weren't just molded; a hand-painted glass shade was decorated by hand, one at a time, bringing real decorative craft to fixtures that might otherwise have been plain. These shades carry small differences molded glass can't, and they're among the more special, and more fragile, shades to survive.
The decoration came in several forms. Some shades were hand-painted with florals, scenes, or geometric Deco patterns, the paint fired onto the glass or applied on the surface. Others were reverse-painted, the design applied to the inside of the shade so it glows through when lit and stays protected from the outside. In each case, a person decorated the piece by hand, so no two are quite identical, and the best of them show real skill. At domestic scale, this brought a touch of luxury to ordinary rooms, the kind of detail a mass-molded shade couldn't offer, at a price a middle-class household could reach. The fragility is the catch, in two senses. The glass breaks like any shade, and the decoration itself is vulnerable, surface paint can wear, flake, or be scrubbed off by a careless cleaning, so a shade with its original hand-painted decoration intact and bright is less common than a plain survivor. Reverse-painted decoration survives better, protected on the inside, which is part of why that method was used.