Gray nails are an infection of the nail plate and nail tissue underneath caused by a fungal infection. Generally, gray nails appear because one already has a fungal disease themselves, or someone living closely has a fungal disease, such as ringworm, tinea pedis or ringworm, or someone living closely has these diseases, and sharing intimate items with them, like towels, washbasins, bath towels and nail clippers, may cause the fungus to spread. Other patients get it because of their own poor health, such as having a systemic disease, like diabetes or problems with the local peripheral blood or lymphatic system. Some patients get gray nails due to trauma to the nail, where there is obvious trauma, like fungus and bacteria can invade directly under the nail through the broken area and cause infection.