Lead (Pb) in plasma

Lead glows violet, and it is one of the purest violets in the collection: the strong line at 405.8 nm sits right at the edge of what the eye still reads as colour rather than darkness. The ring itself saturates to pinkish white while the whole vessel fills with that ultraviolet-adjacent haze. Cameras cope with it badly, which is saying something for an element this photogenic.

Periodic Table of Plasma