Primitive nails dating
Discoloration, thinning, thickening, brittleness, splitting, grooves, Mees' lines, small white spots, receded lunula, clubbing (convex), flatness, and spooning (concave) can indicate illness in other areas of the body, nutrient deficiencies, drug reaction or poisoning, or merely local injury.
It is just under the free edge, in that portion of the nail where the nail bed ends and can be recognized in fair-skinned people by its glassy, greyish colour.
Actual growth rate is dependent upon age, sex, season, exercise level, diet, and hereditary factors.
and the composition of the nail includes 7–12% water.
When the pressure is released, the normal pink colour should be restored within a second or two.
Delayed return to pink color can be an indicator of certain shock states such as hypovolemia.