The term "Blue Diamond" typically refers to a rare and valuable gemstone known for its striking blue color. This color is primarily due to the presence of boron in the diamond's crystal structure. Blue diamonds are among the most sought-after gemstones, often fetching high prices at auctions and in jewelry markets. One of the most famous examples of a blue diamond is the Hope Diamond, which is renowned for its deep blue hue and storied history. Blue diamonds can vary in shade from light blue to deep, vivid blue, and their rarity makes them a symbol of luxury and prestige in the world of gemstones.