These dice are all metallic in color, but are not actually metal dice, nor do they have metallic pigment. Instead these are color combinations that dice manufacturers use to provide metallic-looking dice for much lower prices. To be fair, these dice are metallic looking-ish -- without actually metallic pigment they can only get so close, and these dice tend to lack the signature metallic sheen. There's still some cool-looking dice, just don't expect them to really look like they're made of metal. Because they don't.
We have metallic-colored dice in:
7-Dice setsof blue dice (D&D, Pathfinder, Earthdawn, Cthulhu, and many RPGs)
10 d10 setsof blue dice (World of Darkness, including Vampire & Changling)