I’s guess some ceramic or wood piece was originally there.
It’s described as handmade brass with decoration that appears to be from the art deco (or maybe art nouveau) era, teens to late thirties more or less. Would somebody have a handmade silent butler in this style, then repurpose it and put a window and a “gemstone” in the former handle?
It’s an oddity, this thing. I’m really thinking some ceremonial use, maybe brought over with immigrants or something. Contained some special object that was shown. Way too small for Torah scrolls.