For a unique look, experiment with unusual gemstones, such as pink morganite, black chalcedony or steely hematite.
Morganite is the light pink to violet-pink variety of beryl. Chalcedony is a type of quartz, and includes both onyx and agate. If you're looking for a chunky ring for a man from mars, consider a ring with hematite. This magnetic mineral is iron ore and it's usually a silvery titanium colour but it can range from black to brown, reddish brown or even red.