But when thinking about white metals, white gold isn't the only choice available in fine jewelry; platinum is another popular white jewelry metal. These metals have very distinct characteristics. Understanding these differences will help you to determine which white metal is right for you.
White gold is created by alloying yellow gold with such metals as nickel, copper, silver and zinc to get a white hue. In addition, white gold pieces are often covered with a thin plating of rhodium (one of the platinum group metals) to strengthen them and give them a whiter appearance. This finish wears off over time and the plating process may be repeated. White gold has the same properties as yellow gold - meaning that 18-karat white gold is 75% gold mixed with 25% other metals. It is highly reflective and is not subject to tarnish. It also is less expensive than platinum. On the negative side, white gold isn't as pure, rare or durable as platinum - and it sometimes displays a yellow undertone.
In comparison, platinum is a white metal that is denser, heavier and stronger than gold. Platinum used for jewelry is much purer than gold. Measured in parts per thousand, platinum jewelry is typically 850-999 parts pure platinum (85%-99.9%), with the remainder made up of other metals. This purity makes platinum hypoallergenic. Like white gold, platinum provides an excellent backdrop for the sparkling white of diamonds. It is the rarest jewelry metal and has a deeper, more luminescent white hue than white gold. The biggest negative against platinum vs. white gold is its higher cost - in some cases, a platinum piece may cost nearly twice the price of a comparable white gold piece.
Graduate Gemologist, GIA
Certified Appraiser