Fittingly dubbed the “Russian Nesting Doll Diamond,” this tabular-shaped diamond within a diamond was found in the Nyurba mine in Yakutia, Russia. Perhaps the world’s first-ever instance of such a gem, an outer diamond (.62 carats) holds a smaller one (.02) carats within, but the two differ enough so that the smaller rock rattles around inside. Because this is such a rare occurrence, researchers have yet to assign it a monetary value and scientists have no explanation for how it formed. They do know, however, that it’s roughly 800 million years old. Read more at Popular Mechanics.