Got some suggestions, and Elizabeth at The Lacquered Lizard was correct:
it's Chanel Cry Baby!
How do I know? Well, Li Lian from shortwidenails looked through her Seventeen magazines, and confirmed it:
Gorgeous, right? Unfortunately, it's sheer and doesn't appear like it does in the picture, but MYSTERY SOLVED, folks! So if you know of a polish that looks on the nails like Cry Baby in the picture, tell me tell me!
Thank you to everyone who helped, especially Elizabeth and Li Lian!!!