Steel, as every schoolchild knows, is not an element. Though Steel may have the more dramatic name, his personality is that of iron: cold, dark, hard, a blunt instrument.
Sapphire is also not an element - it is aluminium oxide, corundum - but Sapphire has little in common with aluminium or oxygen. She is brilliant, polished, attractive, and harder even than steel.
Silver is an element... but the technician Silver does not take his nature from the easily tarnished metal. He is quicksilver: Mercury. He dances and gleams and deceives the eye.