There are dozens of knock-off companies that make replica Birkenstocks, and in some places sellers may try to pass off the replicas, telling you they are the real thing. Birkenstocks are expensive shoes with patented soles, and while some of the knock-offs may look similar, appearance is where the similarities end. In order to make sure you are getting authentic Birkenstocks, there are a few tips you can use to identify a fake.

Inspect the box. Authentic Birkenstocks have a photograph of the actual shoe style on the outside of the box. You may also want to open up the box to make sure the shoe inside is the same shoe pictured on the box.

Look for the foot-width stamp on the box and on your Birkenstock. Birkenstock marks their shoes with a special barefoot stamp to let customers know if the shoes are wide fit or narrow fit.

Check for the Birkenstock logo on the sole of the shoe with the registered trademark symbol beside it. It will also say "Made in Germany" just below the logo. A fake shoe might misspell the name, or not include it at all, so make sure you check the spelling carefully.

Test the weight of the shoe against an authentic Birkenstock. Many knock-offs are heavier than authentics, and you can feel the difference just holding them in your hands.The only time this would not be the case would be if you were testing the weight of "Birkis," an authentic brand made by Birkenstock. They tend to be lighter weight than Birkenstocks. Consider using the Birkenstock Website or a Birkenstock retailer to compare shoes you're not sure are authentic.

Check for a "Made in China" stamp on the shoe. If the Birkenstocks you have purchased online, or are looking at in a shop say "Made in China" on them, they are not authentic Birks.