Rubellites and copper, and copper luster tourmaline. The presence of copper in tourmaline, especially in varieties that are typically black or dark, can result in fascinating visual effects. Copper ions can substitute for other metals in the tourmaline structure, leading to colorations that range from subtle pinkish or purplish hues to striking metallic lusters and iridescent sheens. These copper-bearing tourmalines are often highly prized for their unique appearance, which sets them apart from standard tourmaline varieties. In Singapore, where collectors seek gems with distinctive characteristics, these copper-infused tourmalines are gaining attention.