Yellow Gold: Pure gold which is always yellow is too soft for jewelry use. The metals that are mixed with pure gold for strength can also modify the color of gold resulting in different shades of yellow, white and rose gold.
White Gold: Was originally developed to imitate platinum and is usually an alloy containing 25% nickel and zinc.
Rose Gold: Is created by increasing the copper colored alloys normally found in the composition of gold and decreasing the silver colored alloys zinc, nickel.
If stamped 18kt it contains 75% pure gold
If stamped 14kt it contains 58% pure gold