A good practitioner should be able to distinguish between healthy or weak organs by carefully examining the fingernails' appearance. Nails never finish their cycle of growth and, thus, are an accurate record of a person's systemic and physical situation.
Nails are the transfer points for all nutrients in the body. Blood runs through these specific points, which are the meridian points in the body. Many physical deficiencies can be seen in the appearance of the nails. If in good health, the nails will be shiny in luster, pink and transparent, with a smooth arch.
In addition, many meridian lines run along the tongue, and thus the tongue is an important location of bodily function. When the body is not functioning correctly, it is reflected on the tongue. For instance, one will notice that during sickness, the tongue will appear duller and perhaps a different color and texture than when one is healthy.
Thus, the fingernails and tongue are reflective of your internal health.