The Koh-i-Noor. 105-carats, oval-shaped, and arguably, the world’s most famous diamond. Today, it’s set among 2,800 other stones in the Crown Jewels, but it hasn’t always been there.

They are also very large. The Koh-i-noor – now part of the British Crown Jewels – weighs a whopping 105.60 carats. The Hope diamond, housed in the Smithsonian’s National Museum of Natural ...