Coloured stone refers to gemstones or minerals that exhibit vibrant hues due to their unique chemical compositions and structural properties. Common examples include sapphire, emerald, and ruby, each valued for their beauty and rarity. These stones are often used in jewelry and decorative items, enhancing their aesthetic appeal. The color of a stone can be influenced by factors such as impurities, light absorption, and crystal structure. Some stones, like amethyst and topaz, can also change color when exposed to heat or light. Collectors and gemologists study these characteristics to determine the quality and value of coloured stones.