Attached is a photo of how the HW clasp started out and the two vintage UG clasps that I emulated as I attempted to guess what UG may have done had they made a deployment clasp in the 1950s.
My Tri-Compax was manufactured in the early 50s, perhaps 2-3 years before this logo was registered, regardless I think "it works well" on the watch. I am a fan of deployment buckles as they seem much safer and easier to use. After some research I learned they were invented by Louis Cartier in 1910, so I felt less bad then putting one on the 1950s UG.
Took a bit of work to find a clasp as there were no solid gold generics that I could find. I got lucky with this NOS HW clasp that was for sale essentially for its weight in gold. The jeweler then fitted a gold plate over the HW initials and laser engraved the logo on the brushed plate.
I think it's good that you are publicly documenting it so that nobody tries to pass it off as genuine in the future. I'm not sure what the new owners are going to make of this sort of thing - it's a different matter now that it's no longer a dormant brand.
The other interesting question is whether UG are going to get very tedious with vintage owners who might want to buy a new clasp for an old watch assuming they become available. I had a surprisingly helpful response from Nivada Grenchen recently when I asked if I could buy a couple of new 16mm signed buckles for some vintage models (but I also have one of their mecaquartz reissues).
No worries, my grandfather’s watch has been in the family since the 1950s and it is not for sale, nor will it ever be. I’m not a collector, dealer or trader of watches. Engraving a logo on a vintage watch buckle that is for personal use is generally permitted under trademark law as long as it’s not sold as an original UG buckle and it is strickly for private, non commercial enjoyment.