Titanium?

Lighter than steel, but just as strong, it has become very popular, especially in wedding rings and men's jewellery, replacing platinum or white gold at a lower cost. Being completely hypoallergenic, it is used in the manufacture of many piercings. Titanium does not tarnish and is very resistant to wear. Its surface can be polished for a high-gloss platinum or brushed for better scratch resistance. Depending on its treatment, its colour can vary from pink, purple, green, blue, turquoise, black and even gold.