This is two polishes made by Wet n Wild, Fantasy Makers Purple Potion and Wet n Wild Fast Dry (although as always, the label is unreadable) Buffy The Violet Slayer:
I was wondering if Purple Potion has a jelly base or not, so I googled, and found Vampy Varnish's swatches, and it says that no, it's just a black base. I was really enamored of Purple Potion when it was new (and even more enamored of Creepy Pumpkin, which is also swatched there, so much so that that bottle is long-gone) but I seem to have gotten over this one a bit in the intervening years. It looks sort of like Revlon Scandalous/Lippmann Bad Romance with less glitter - although that's not really fair, either, because the glitter in this one is darker and I don't think they were trying to dupe Bad Romance, particularly (although this was apparently released about a year after it so you can't rule it out, either) - or if so they did a bad job of it!
Buffy the Violet Slayer is, well... I almost said it was just another purple shimmer, and then I thought it over and decided it's a very nice one indeed - it's brighter than it appears here, as I recall. (Scrangie agrees. And hmm, I have three out of the five polishes in that collection. I had no idea that this and Gray's Anatomy and Party Of Five Glitters were all the same collection, although come to think of it maybe I should have been tipped off by the TV-show names.) Despite the similarity in the swatches, I don't think that BtVS and Amethyst (above it on the wheel) read as much alike as you might think. Amethyst is very pretty too, but but it doesn't have the brightness of BtVS.
(Buffy The Violet Slayer is apparently still a current color, and so are most or maybe all of the colors in that collection I mentioned above. I haven't seen the tombstone bottles around at Halloween for a couple of years now, so I definitely wouldn't hold my breath waiting for it to come back this year either. Although damn, somebody needs to dupe Creepy Pumpkin, if not.)