Blue back light on 128*64 lcd

I want the 128*64 ks0108b compatible lcd screen with the blue back light. How do I make sure of this when I order?

Do you mean lcd work with blue back light? The only backlight is Yellow Green. It can not work with Blue back light.
Or if you want to display data with blue color, you can set Display Data =‘1’. More information in datasheet.