From wikipedia,
Onyx - A banded variety of chalcedony, a cryptocrystalline form of quartz.
Ruby - A clear, deep, red variety of corundum, valued as a precious stone.
Crystal - A solid whose atoms (or molecules) are arranged in a repeating pattern. Crystals are found naturally or can be made artificially.
Someone should use Diamond for the next programming language, really like the wiki definition.
Diamond - is a carbon crystal formed under heat and pressure.