Hi all - I learned on a Stella 12 String which my Mum bought for me as a present - had Black Diamonds on it. No truss rods then and because it had been tuned to concert pitch the action was about 1.5 inches (it felt like that) I used black diamonds for quite a while until in the late sixties they became rare in the UK.
Nowadays, when I can afford decent instruments, I know that my fingers were toughened up the hard way and I have never since had problems playing.,

Does anyone remember Cathederal Strings - made by the Cathedral Music & Tennis String Company - I think they got the two mixed up along the way but my Tennis Racket could make a fine sound when played the right way.
Keep playing - happy Christmas