The stone that arrived on a comet

Added: 2026-05-19

[00:00:00]There is a gem that's sparkles more than diamonds. It costs a tenth as much and it came from space. In 1893, a French chemist named Henri Moissan was examining rock samples from the Canyon Diablo in Arizona.

[00:00:13]He found a mineral nobody had ever seen, a clear crystal that outsparkled a diamond.

[00:00:19]He thought he had discovered a terrestrial mineral. Well, he hadn't.

[00:00:23]The mineral arrived on a comet. It is silicon carbide. On Earth, it almost doesn't exist. Geological conditions don't allow it to form here in any quantity. Almost every natural sample of moissanite ever found has been extraterrestrial in origin. Embedded in meteorites or trapped in extremely deep mantle inclusions.

[00:00:43]The optical properties are what makes it interesting. Moissanite has a refractive index of 2.65 against diamond's 2.42.

[00:00:51]Per carat, moissanite returns more light than the diamond.

[00:00:55]Today, it is grown in laboratories from the same starting compound. The diamond industry calls it a simulant. Well, it isn't. It's a real mineral with its own crystal structure, its own science, and its own history. It just happens to be the gem that arrived on a comet.