Melanite garnet is a variety of Andradite; an opaque black stone with a great vitreous lustre that looks great when cut in facets that catch the light.  It's an increasingly popular stone, given the general scarcity of black gemstones, and is a nice, elegant stone that looks great with silver.  If you are after something black and sparkly it's a good choice, being less expensive than black diamonds, spinel or sapphire, and yet superior to less expensive stones such as onyx and jet.