well-maintained early 20th century antique american arts & crafts or craftsman style art glass lamp fixture attributed to r. williamson & co., chicago, il. the lampshade is comprised of riveted joint, pressed and folded yellow brass strips of metal, enclosing four matching richly colored red and green opalescent or "slag" glass. the outer edges of the pyramidal-shaped fixture contains evenly-spaced ruby red glass multifaceted jewels. the rolled rim fitter remains in good overall condition. the nicely aged surface patina was left untouched.