Blue sapphire is a variety of the mineral corundum, which is composed of aluminum oxide. Blue sapphire ranges in color from pale blue to blue-black and is prized for its rich hue. Blue sapphires are found in a wide variety of colors, including pink, yellow, green, and orange. Sapphires are commonly used in jewelry, especially rings and earrings. Blue sapphire is the birthstone for September. Blue sapphire is a popular choice for engagement rings and other special occasion jewelry. Sapphires are durable and scratch-resistant, making them ideal for everyday wear. Blue sapphire jewelry is typically set in gold or silver.