The only sure way to know if you are getting the real thing is to buy from a flagship store or a reputable department store. However, if you are trying to save money and buy it used or online, that's where you can really be duped.
Buying couture brands on the Internet is easier than ever before, but those who plan to drop hundreds or even thousands of dollars take a risk.
San Mateo resident Helen Tsai collects Diane Von Furstenberg dresses and frequently buys used on the Internet. She said, "Looking at the pictures, I thought I was getting the genuine article. But when it came in, it was very obvious it was fake. The fabric was polyester as opposed to silk."
Since then Tsai has turned to sites and buyers that guarantee their authenticity, like a new site called Lollipuff.
"We are the only auction site where we guarantee that every single listing on our site is authentic," said Fei Deyle, the CEO of Lollipuff.
Deyle founded Lollipuff and was a professional authenticator for many years. She has helped many people get their money back when they were duped into buying a counterfeit on eBay. Some of eBay's most well-known consignment stores pay Fei to do authentications. Deyle says there are some things that everyone can look out for to spot a fake.
"A lot of counterfeit, but not all, will be missing other tags such as the care label and the hanger tags," said Deyle.
Goodwill gets so many valuable donations that they have created a store on eBay. Mitali Thakur works as an authenticator at Goodwill's San Francisco headquarters.
"Stitching, quality of leather, fabrics, the details of any particular design, these are the things we look for," said Thakur.
Matali says it's generally fairly easy to identify a fake, but there are some brands that can be difficult. The hardest one to guess is Coach because Coach has really good knockoffs. Chanel puts authenticity cards in their purses, but counterfeiters sometimes go so far as to include a knockoff card.
"Anytime you see a bag with an authenticity card that has this rainbow effect, you know that bag is a counterfeit," said Deyle.
The real ones have a matte, gold border. Something to look for in expensive shoes is leather soles.
"High-end brands like Louis Vuitton, the sole is made out of leather and so there's a natural curvature to the way the leather drapes across the shoe," said Deyle.
And, if you have the shoe in hand, you can tell a fake by the way it sounds.
"When you actually knock on it and scratch it you can tell it's made out of plastic," said Deyle.
Goodwill's director of marketing Tim Murray says you will only find their high-end, well taken care of couture donations in their eBay shop. And, they follow the law with the fakes.
"Anything that is proven beyond a shadow of a doubt to be counterfeit, we dispose of," said Murray.
The law also holds the importer of counterfeit goods liable. U.S. Customs and Border Protection import specialist John Gerber says if a counterfeit item headed to you is seized before it even arrives at your doorstep, you are the importer and you are liable.
"The penalty is equal to the domestic value, as if they were genuine goods," said Gerber.
So, if you are buying a counterfeit Coach purse for $12 and its real value is $1,000, you could be penalized $1,000 if you buy it. If you think you've bought a fake or have spotted a fake, there are a few organizations to report offenders.