16.5 inches long. Both rubies and sapphires are varieties of the corundum mineral and have the same crystalline structure. What differentiates sapphires from rubies is the color; while rubies are always red, due to inclusions of chromium in the gemstone's structure, the color of sapphires varies due to different metal inclusions from the well-known dark blue to light blue, pink, yellow, orange, green, and white.