Red, gold and bronzed hooks are sharpened before they get the gold, bronzing or red applied. Black chrome is a hard metal and is sharpened after its applied.. The sharpening process does not go thru the plating so rusting is not at issue. While gold is a metal, the plating is very thin and any sharpening done after the plating is applied would remove the gold and cause rusting right away. The temperature needed for gold plating also changes the temper of the steel in those hooks making them very brittle. A red hook with gold under the red will also be a very brittle hook. Black chrome, black nickel...one in the same. Sharp from the get go and only vigorous resharpening will remove the plating and allow them to rust.