I'm pretty sure that your vase is post 1960. Like you, I don't think it makes a difference as it's a gorgeous piece. I could live with a bruise. In fact, my other Kraka piece has an internal fracture near the top, which lead to me getting it for $9.99. I still display it.
I took my information from a chapter by Ulrika Ruding, "Signatures techniques and designers," in Wickman, 'Orrefors.' Rereading Ruding, she says that production of unique pieces continued after 1960, at the same time as they were making multiples of some designs.
I also have 'Glas in Scweden' by Ricke, which Ivo quotes as a source of his information. However, it's in German, which I don't understand at all. However, it does seem to show the original series inscribed with an 'Nr' before the number. I couldn't usually afford this level of glass(you can take me out of Scotland but you can't take....). It was on an online auction with a ridiculously low starting bid. I put in a bid and was the only bidder.
Perhaps Ivo will drop by again and clarify for us.