Our new to us Mid-Century Brass Lamp with crystal & brass lampshade

Over Thanksgiving, we went to South Florida to buy a sofa table from a person on Craigslist. When we got there, he was also selling this very heavy brass lamp. The lampshade is also brass, with Crystals that have been soldered into it. He said his parents bought it around 1960 in the New Jersey/Philadelphia area.

We have never seen a lamp like this before but I think it is maybe a GIM lamp since one piece has GIM 152 on it. We would like to know what company made this lamp. It is 35" tall from the bottom of the base to the top of the finial on top.