Why do gemstones have bright colors?
As with many things in life, when it comes to gemstones, looks can be deceiving. While all are beautiful, rubies, sapphires, and diamonds each attain their brilliant color through different means. Transition metals can transform even the plainest crystal into a coveted treasure. Causes of color in gemstones When impurities are added to colorless gemstones, brilliant colors are frequently produced. When chromium is added to colorless corundum, a red ruby is born, and a green emerald emerges when chromium is added to colorless beryl. Diamonds can be colored blue or yellow by the addition of impurities. The role of impurities in causing color is different here Through yet another mechanism (charge transfer), the addition of impurities to corundum can produce a deep blue sapphire. Amethyst’s violet tint is the result of iron impurities in crystalline quartz, although this impurity acts differently than the chromium impurity that produces the red color of ruby (see color centers). Many gems
