What health signs do fingernails tell in Traditional Chinese medicine?

In Traditional Chinese Medicine (TCM), fingernails are believed to reflect the health of the body's internal organs and overall vitality. For instance, pale nails may indicate blood deficiency, while dark or bluish nails might suggest poor circulation or an underlying cold condition. Brittle or ridged nails can signal issues with the spleen or kidney health, and a healthy, smooth nail is often seen as a sign of balanced internal energy (Qi) and good health.