Blue color is like a washed denim (not too dark or too bright).  They feel sturdy and are what we have been looking for. There is soft fabric on one side (the blue side). The other side, which is a grey shade of some type of polyester backing, will likely offer both insulation for warmth in the winter and keep sun out in summer.  I love that they will work on all of the windows in the room.  There aren't as many options when looking for shorter curtains, unless you sew your own.  I do not suggest altering these.  Some people may not like the backing as these curtains are not machine washable.  I had similar curtains in the past, that had a similar backing which peeled upon washing in hot water, and I learned my lesson.  I will not put in the dryer either.  They can be hand washed if needed.  So happy to have found them.  Grommets are nice too. Overall, very nicely made and look great!