Irradiated diamonds are stones that have been artificially treated to enhance or change a color. These treatments are commonly used on diamonds that have an undesirable tint to improve their value and salability. For example a P-Q color, which is noticeably yellow but not intense enough to call a fancy yellow, can be treated to darken its level of saturation and/or change its hue. The treatments are somewhat predictable, based on years of experience, but the exact color outcome can sometimes be disappointing.