blue nails blue nails blue nails, or more formally azure lunula, are characterized by a blue discoloration of the lunulae, seen in argyria and cases of hepatolenticular degeneration (wilson's disease), also having been reported in hemoglobin m disease and hereditary acrolabial telangiectases. azure lunula in wilson's disease the blue color involves the lunula (most intense pigmentation) and fades proximally. in argyria, the nail is permanently pigmented a slate-blue color and is most evident in the lunula. minocycline can also turn the nail plate blue-gray.