Fake Diane Vonfurstenberg items are usually not made of silk.  A lot of times authentic items are made in China and will say so on the label.  The label will be underneath the Diane VonFurstenberg tag and will state what the item is made out of.  A lot of DVF items are lined so that is an important sign something is real.  Inside the actual dress/shirt there will be another tag that has numbers on it and if the item is maternity it will say that as well.  Hope this helps a little!  Also if someone uses a stock picture of an item it usually is a sign that the item is fake, look for actual pictures of the piece of clothing and ask for a picture of the tag.  Thanks!