They can be plated with various precious materials, e.g. diamond and gold, to increase durability. Plate them by placing the armor piece in the center of the crafting grid and fully surrounding it with your chosen material. The upgraded scale armor has the same armor contributions as their corresponding vanilla counterparts.
Scale Helmet (0.5 Armor Points)
Scale Chestpiece (1.5 Armor Points)
Scale Leggings (1 Armor Points)
Scale Boots (0.5 Armor Points)
The Scale Armor can also be "plated" with precious metals, e.g. Iron, Gold or, Diamonds which increase its protection rating.
It is only as good as the type of armor you plate it with. I.e. Diamond plated will only be as good as normal diamond armor.