Grandidierite – $100 Million/Kg

First discovered in 1902 on the island of Madagascar, grandidierite is a rare mineral named after Alfred Grandidier, who happened to be a scholar of natural history in Madagascar. This rare gem is characterized by strong levels of trichroic pleochroism, which means that the mineral appears to have three different shades of colors when viewed from different angles.

On the other hand, in some cases, grandidierites appear bluer than usual due to higher levels of iron in their structure. If you feel frisky and wish to splurge this rare gem on your future spouse, be prepared to spend at least $20,000 per carat.