Besides considering how much you'd want to spend and the colour that goes best with your bedding, there are some key details about silk you should look out for.
Firstly, you should make sure the pillowcase you're buying is made from natural silk if you're wanting to benefit from its properties. Lilian Wu, marketing manager at LilySilk, says holding a flame to silk can be a way to distinguish between real and faux silk. Genuine silk produces a smell similar to that of burning hair with an invisible flame that will soon self-extinguish. Fake silk will combust rapidly with an intense flame followed by the smell of burning plastic. So maybe don't test this out at home...
Secondly, find out the momme count. "Momme (mm) is a unit traditionally used to measure the quality of silk fabrics," says Wu. "Usually, the higher the momme weight, the more durable the weave, the more luxurious the fabric is, the more suitable it is for heavy-duty use, and the longer it will last."