Bleu Cobalt

This is YSL Bleu Cobalt, although obviously it's missing its trademark cap:

If I didn't know where this came from I would worry about the missing cap, and wonder if it was really Saint Laurent, but I do know its provenance, generally - I got it in a box from my sister, who was working in a department store at the time. I assume it's real and the cap just got lost somewhere along the line. I would say it might have been a tester, but if it was it never got used at all. (My guess is that my sister got it for free or nearly so, although I never asked. She sent me boxes of random-ish stuff like this at the holidays a couple of times, things that presumably had been marked way down for one reason or another. As I understand it, that was just a perk of working there.) Anyway, lovely shimmery deep blue. The polish below it is Essie Starry Starry Night - reformulated version - and the base color there looks pretty much identical. In the bottles they look pretty identical as well, although on the nail of course SSN has that glass-fleck sort of texture, or whatever it is in the new version. (In the original it was supposed to have been actual diamond dust, right?)