It's doubtful anyone will be (a) knowledgeable enough (b) get up close enough to your ears to tell the average pair of CZ studs from real diamonds. Unless you're an expert, nobody will know until they look at the backing and realize it's not a screw-back which would keep real diamonds secure on the ear.
Neiman Marcus carries a line of faux diamonds called Fantasia... they're not at all cheap, in terms of CZs, but they're probably the most realistic you'll get.