1. True Blue Sparkle: When most people think of a sapphire, they picture a brilliant, deep blue gemstone. But did you know that sapphires actually come in almost every color of the rainbow—including pink, yellow, green, purple, and even white—except for red? (Red sapphires are called rubies!)

2. Built Like Diamonds: Sapphires are some of the toughest minerals on Earth. On the Mohs hardness scale (which measures how hard rocks and minerals are), sapphires score a 9 out of 10. The only natural thing harder than a sapphire is a diamond!

3. Birthstone for September: If you happen to be born in September, the sapphire is your official birthstone. People have worn it for centuries as a special token representing wisdom, loyalty, and good fortune.

4. Royally Famous: Sapphires are a favorite of kings, queens, and celebrities. One of the most famous pieces of jewelry in the world is a stunning blue sapphire engagement ring that originally belonged to Princess Diana and is now worn by the Princess of Wales.

5. Scratch-Proof Watch Screens: Because sapphires are so incredibly hard and tough to scratch, scientists figured out how to grow synthetic (man-made) sapphires in labs. Today, companies use clear synthetic sapphire glass to protect the screens of high-end watches and smartphone camera lenses!

6. Named from the Sky: The word sapphire comes from ancient Greek and Latin words that mean "blue stone." Some historians believe it might also be linked to an old word meaning "beloved of the planet Saturn."

7. Museum Superstars: The Smithsonian Museum of Natural History in Washington, D.C., is home to one of the largest and most famous blue sapphires in the world—the Logan Sapphire. It weighs a whopping 423 carats and is about the size of a large plum!