sapphire

Sapphire is a precious gemstone known for its striking blue color, though it can occur in other hues. It is a variety of corundum, a durable mineral composed of aluminum oxide. Sapphires are valued for their hardness, ranking nine on the Mohs scale, making them suitable for jewelry that lasts over time. Naturally formed deep within the Earth's crust, sapphires are often mined and then cut and polished to enhance their clarity and brilliance. Aside from jewelry, sapphires are also used in high-precision instruments and electronics due to their strength and thermal stability.