Filed under: CosmeticsFall is a great time to try out darker shades of nail polish, eyeshadow, and lip color. But how dark is too dark? Yves Saint Laurent sent black-as-night lips down the runway during its fall fashion show, and the company will offer the signature shade for sale next month. (You can pre-order a tube of "Pur Black" here for $28.) But though it may come as a surprise, you don't have to be an avant-garde fashionista to work this look. Even mainstream cosmetic companies, like Lancome, are in on the trend. Lancome's ink-black "Piha" gloss will go on sale, as part of a set, in November. Unlike the YSL version, Lancome's is glittery, and meant to be layered over the red lipstick that it is sold with. So while matte, black lipstick is still a fashion miss, these high-shine black glosses don't have to be. Aaron May, Lanc