'GW' Countermark / Counterstamp - any info / theories on it? PCGS and NGC examples

@U1chicago said:
I found this coin on GC and thought the combination of a straight grade and "Possible Fantasy" on the holder to be unusual. Has anyone seen that before? I did some searching and discovered that there is no consensus on what the countermark is and when it was done. Some speculate it is a reference to George Washington while it could also be some merchant or just random initials.
...
From a Heritage listing of several examples, the description says:
"The GW mark in a rectangular depression is controversial, with differing opinions about its age and origin."

I kind of doubt it has anything to do with George Washington personally given it's showing up on coins made long after he died in 1799. I assume it's a contemporary stamp that will never be attributable to anyone.

Have you tried looking up silversmiths that era to see if any matches? Looks like a stamp they would put on pieces they made.

Here is a Stack's description of an 1807 draped bust half dollar:

"Punched almost directly in the center of the host with a small GW mark, in a rectangular cartouche. Believed to be a fantasy issue and found on several different early hosts. These are frequently found in advanced collections, if as nothing beyond a curiosity."