Ayurveda considers nails as the waste product of the bones. If the nails are dry, crooked, rough and break easily, it indicated a predominance of the vata constitution. Soft, pink, tender nails that are easily bent are indication of a Pitta constitution. When the nails are thick, strong, soft and very shiny, then Kapha predominates.
Longitudinal lines on the nails indicate mal-absorption in the digestive system. Transverse grooves on the nails may indicate the presence of long-standing illness or malnutrition.
Yellow nails indicate a delicate liver or jaundice. Blue nails are manifestation of a weak heart. Undue redness shows an excess of red blood cells.