The growth of the nail is longitudinal, that means that the cells grow from the root and they disappear when we cut our nails.
The fingernails of the hand, for an adult’s average, grow approximately 0.1mm up-to-date.
The growth in children is higher and in old people is lower.
The toenails  grow between a third and a fourth more slowly. So, in order to regain one fingernail delays between five or six months and one of the toenails between 15 and 18 months.
 
The fingernails are flexible in the children, transparent, of flat and convex surface.
In adults, the fingernail is harder and  resistant appraising always the presence of the half-moon at the cuticle’s zone.
In older people, the fingernail lose brilliance, it becomes opaque, grayish, fragile, and the half-moon tends to disappear.
A healthy fingernail has an oval shape, is flat and with a partially pink color. This pink color is due to the existing a blood flow in the bed of skin and to the transparent characteristics of the nail.
The fingernail then, as well as for its color like for its distinct forms, constitutes a mirror of our healthy status.