Bought from an authorized dealer be they new or used?
Bought from a local golf shop that warrants authenticity?
Bought from a local golfer on a one to one basis?
You need to be able to trust the seller.
If you bought it through what I refer to as garage resellers through a site like eBay, then the odds are higher that they may be fake and if not authentic, then recourse may not work out well. They can be authentic but others can slip through.
If you are in the US and bought them online and they were shipped from outside the US, odds are they are counterfeit.
The old saying applies. If the price is too good to be true, it isn’t. Counterfeits are getting so good, they are hard to distinguish on a photo here.