Let us know how the shave with De adapter and Gem 1912 goes for you!I’m reviving this old thread because there are few out there still interested in doing this, including me.
FWIW, I returned to traditional wet shaving for environmental reasons. I was getting a good enough shave with cartridge razors, but I didn’t like throwing away all that plastic. My intentions were to get the most bang for the buck and use DE blades. Then I found a small lot of razors which included a Gem 1912 series, which I didn’t think I would use. But I went down that rabbit hole Since then I’ve been pursuing how to double my shaves per blade on vintage SE razors.