I saw a documentary on The History Channel about tehelet dye, used in the fringes of Jewish prayer shawls and at the corners of garments. The blue color is supposed to remind the wearer of God and the commandments. The fascinating thing about this dye is that, kept indoors during the drying process, it becomes Tyrian purple, but when brought outside to dry, it turns blue (or tehelet) because of exposure to ultraviolet light.
I have imagined the robes of the Luatian clergy to be blue and white, though the color they use is a paler hue than true tehelet.
The secret for making tehelet dye was lost for centuries until some scientists figured out that the hillazon was probably the Murex snail, the same one used for making the Romans' Tyrian purple dye. Fascinating stuff!