Lunula that have a blueish tint could suggest Wilson’s disease, a rare inherited genetic disorder in which copper accumulates in the liver, brain and other organs. Red lunula may indicate heart failure, research shows. And in patients with severe kidney disease, it’s not uncommon to see half-and-half nails, where the white from the lunula extends halfway up the nail bed, and the other half of the nail is darker in color, says Dr. Richard H. Flowers, assistant professor of dermatology at the University of Virginia.