The famous Ugg Australia brand is made by Deckers. If is that, you can use the follwing ways to confirm whether it is spot imposters.
- Christmas UGGS Sale have a large middle G on the logo.
- They have real sheepskin fur inside: fakes often use synthetic.
- They are made in New Zealand, Australia, and more recently, China.
- If you want to check that a retailer is legit, email Deckers at email@example.com and ask if that retailer is licensed to sell Ugg Australia.
- Alternatively, you can check the on the official UGG Boots Christmas Sale website to see if the the website you're thinking about buying your boots from is on its legitimate online retailer list.
There's an interesting explanation of the history of the Ugg trademark on Wikipedia.