"Some fabrics, like leather and denim, might cause permanent discoloration that will not wash off," Apple warns card owners.
The BBC rounded up a number of Tweets from early adopters confirming that the physical card might look nice when you get it, but probably not for long after. "I can say from two months of having the card in my leather wallet, it no longer looks pretty," one owner wrote.
The damage is cosmetic only; the card will still work at a point of sale if you dare to keep it in your wallet. If you would like to keep it looking new, however, Apple recommends wiping it gently with isopropyl (rubbing) alcohol using a soft microfiber cloth.