<unk>  is a black or brown pigmentation of the normal nail plate, and may be present as a normal finding on many digits in black patients, as a result of trauma, systemic disease, or medications, or as a post-inflammatory event from such localized events as lichen planus or fixed drug eruption.
Melanonychia
Leukonychia
Paronychia
Platonychia
Anonychia
Aspermia
Koilonychia
Pellagra