Bright blue pigment (6)
I believe the answer is:
cobalt
'bright blue pigment' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cobalt that I've seen before include "Silvery-white metal used in alloys" , "Magnetic-alloy element; a blue" , "Sort of blue" , "Magnetic metal" , "Metal element" .)