Rubies and sapphires are two of the most popular and valuable gemstones in the world. They are both varieties of the mineral corundum, with rubies being red and sapphires being blue. Rubies and sapphires have been prized for centuries for their beauty and durability, and they are often used in jewelry and other decorative items. The word 'GEMS' is an appropriate four-letter term to describe these two precious stones.