SpeedrooGuessroo · All speeds

How fast does light travel in a diamond?

446.5 million km/hAbout 277 million mph · Cosmic

About 124,000 km a second; slowing light is what makes diamonds sparkle.

That's about 8,000,000 times a red kangaroo's top speed (56 km/h).

446.5 million km/h
a supernova

By speed: light in diamond is about 12× faster than a supernova.

Think you can guess? Play today's Speedroo

Things about as fast

Many real things vary, so we use a typical or official figure. Spotted a mistake? Email [email protected].