Paint the roses

Enchant artifact or enchantment.
Choose a color. All instances of colored mana
symbols and color keywords that are not the
chosen color are changed to the chosen color's
mana symbol or color keyword.
"Why the fact is, you see, Miss, this here ought to
have been a red rose-tree, and we put a white one in
by mistake; and if the Queen was to find it out, we
should all have our heads cut off, you know."