Black diamond is a kind of natural gem, and its color mainly comes from internal impurities and structural defects, not through fluorescence. Black diamonds do not show the characteristics of fluorescence under light. Fluorescence is often caused by specific fluorescent impurities or special structures in gems, while black diamonds often do not have these characteristics. Observing the black diamond under the light, you won't see obvious fluorescence effect. This is also one of the unique characteristics of black diamonds, which is highly sought after in the jewelry market.