In shampoo commercials, the hair you see swinging is lustrous. It is brilliant, in the shiny sense.
Lustrous has its root in the Latin lustrare which means "to illuminate or shine light over." When something is lustrous, it reflects light in a glossy and shiny way. A bright smile and a glowing reputation are both lustrous. If someone has a long and successful work history, you might say their career is illustrious, meaning it has been lustrous for a long time.