No as Saturn is the 12th lord in your horoscope you should not be wearing Blue Sapphire as being the 12th lord Saturn will give you malefic results. Incase you need to improve your Saturn then you may do the Saturn remedies like given below:
1. Help Old people on Saturdays. This can be monetary as well as physical help.
2. Donate some coins every Saturday, you can give to beggars.
3. Donate some Mustard Oil every Saturday.