Sapphire is a precious gemstone known for its stunning blue color, though it can come in a variety of other shades, including pink, yellow, and green. It’s a form of the mineral corundum, which is second only to diamond in terms of hardness, making sapphires extremely durable. The most prized sapphires are deep blue, with a rich, vibrant hue, and they’re often associated with wisdom, royalty, and nobility. Sapphires are often used in jewelry, like engagement rings, due to their durability and timeless appeal. Interestingly, sapphires can also have inclusions called "silk," which are tiny rutile threads inside the stone that can give it a soft, glowing effect.