okay, look, does anyone care? why are you spending so much time looking at fingernails anyway? they filmed for much longer than a few days (although don't ask me how long, i have no idea) and there's no way to stop your fingernails from growing.
Kate Winslet has ugly hands in real life, so my God-Mother's sister was hired by James Cameron to be Rose's hands in all the close ups. Just a little pearl of wisdom for everyone.