They were Gillette safety razors specifically marketed to women. They came in four colors: Dark Blue, Light Blue, Champagne (goldish) and Pink. I think somebody here has a neat photo of the four side by side (Scott?)
Plus they were milder shavers because, obviously, ladies would use them in other places than men would!
I have two blue ladies but I have avoided shaving with them. I already have more soaps and creams than my wife does and with all the colognes and splashes and balms and foofy stuff I now own .... well, I am trying to preserve my manhood!
Aw, cmon. Nobody's looking. It's like a 40's superspeed with a longer, more grippy handle. I promise, I'll put down my binoculars if I see you pick it up.
... wait ...
... um, gotta go!
-- Chet
Generally a "ladies razor" will have a longer handle for reaching down your legs, and will be on the milder side. The early ones are just regular razors in fancy cases, but the later ones like the Lady Gillettes or the injector Lady Eversharp (below) were given a more feminine styling.