Sateen. I somehow missed that on the description or I may not have ordered this duvet set. I was looking for a crip, flatweave percale. I washed this set before putting on the bed, and while the duvet came out of the dryer with no wrinkles, the shams needed a few washes to shake the wrinkles out. The splashy print is a bit cheesy and low res, but from a distance it looks better. I think the ocean blue color is wonderful and it is 100% cotton. The sizing is great for our king down comforter. Still looking for a percale duvet though.