I view the signature razors as part of the corporate infighting between John J. Joyce and King Camp Gillette. The timing is right, according to http://books.google.com/books?id=YCldvmXq25EC&lpg=PA14&pg=PA15#v=onepage&q&f=false and the title juggling documented at Gillette_Timeline. It seems quite plausible that King C. Gillette wanted his signature to be the company logo, among other ideas, while Joyce resisted. Eventually King got the honorary title of President, but the diamond logo went into production and Joyce bought out Gillette's remaining shares in the company.