The Cullinan Diamond holds the crown. Discovered in 1905 in South Africa, it was a whopping 3,106 carats uncut. To put that in perspective, that’s about the weight of a small brick—but way more expensive than any brick you’ll find at your local hardware store.
It was so massive that the mine manager nearly threw it away, thinking it was a piece of glass. Imagine finding a treasure in your backyard and almost tossing it in the trash! That’s the kind of luck that makes you want to check under your couch cushions.
Why Should You Care? (Hint: It’s Not Just for Rich People)
You might think, “I’ll never own that diamond, so why bother?” But here’s the fun part: this diamond is a time capsule. It formed deep in the Earth’s mantle over three billion years ago—before dinosaurs, before your great-great-grandparents, before your neighbor’s cat learned to knock over plants.
Every time you hear about it, you’re hearing a story about geology, history, and human obsession all wrapped in one sparkly package. It’s like the family gossip of the mineral world.
Plus, that diamond ended up cut into nine major stones. The largest, the Star of Africa, sits in the British Crown Jewels. You’ve probably seen it in photos of royal weddings and thought, “Wow, that’s shiny.” Now you can impress your friends by saying, “That’s actually a piece of the Cullinan.” They’ll think you’re a genius.
These are some of the most expensive diamonds in the world: diamond
