A golf ball comprising a core and a cover layer having a cover inner surface and a cover outer surface that treated with and comprises a fatty acid and/or fatty acid salt composition and has a hardness α, the cover inner surface not being treated with and not comprising the fatty acid and/or fatty acid salt composition and having a hardness β. Hardness α is greater than hardness β. The cover layer may alternatively comprise an untreated cover region and a treated cover region that extends inward from the cover outer surface a depth of about 1% or greater of a distance between the cover outer surface and the cover inner surface. Alternatively, the treated cover region may extend inward from the cover outer surface a predetermined depth DCTr while the untreated cover region is disposed between the cover inner surface and the treated cover region a predetermined depth DCUTr.