Faux means fake, or imitation. If you love the look of diamonds but can't afford one, get a faux diamond ring.
Faux is a French word that has crept into our lexicon, because faux in French means "fake." Now if we have the words fake, imitation, and false (all of which are good synonyms), why use faux? For fashion, dahling. Use faux to talk about faux fur, faux gemstones, or to make fun of a "faux pas," which is French for "no-no," widely used among the witty international set when someone does something gauche (French for "clumsy").