Added: 02/17/2006 |
The amazing natural color of white gold ring is light grayGold is a good conductor of heat and electricity, and is not affected by air and most reagents. Heat, moisture, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in gold coins and jewelry; conversely, halogens will chemically alter gold, and aqua regia dissolves it.
White gold ring refers to an alloy of gold and other white metals such as silver, palladium, or nickel. The natural color of white gold is light gray, so jewelry made of white gold is typically coated in highly reflective rhodium (sometimes coated in platinum and palladium), adding a more brilliant shine. Palladium and silver alloys are of higher quality than nickel and are sometimes not coated with rhodium. The purpose of plating is to add luster to grayer jewelry, as well as to prevent oxidation of some of the metals found in the alloys. White gold ring is not platinum, but is used as a cheaper alternative, usually costing one-third as much as platinum.
At the turn of the 20th century, a relatively unknown metal called platinum was being combined with diamonds by some jewelers. However, platinum was very expensive. White gold alloys were developed in the 1920s as a less expensive alternative to platinum. To meet the growing demand, several different alloys based on gold-nickel-palladium, in different combinations, became commercially available. During World War II, the use of platinum and nickel for nonwar-related applications was prohibited. As a result, palladium-based white gold alloys became the only choice for consumers in the U.S.
In addition to higher costs, white gold jewelry based on palladium alloys are denser and heavier than nickel-based alloys. They are also not as white in color. After the war, lower-cost nickel-based white gold quickly once again became the dominant choice of the jewelry industry worldwide. Some people (about 12.5%) are sensitive or allergic to white gold ring. This occurs because of reaction to nickel found in some white gold alloys. Reactions are mild and only involve skin rashes.
Typically, white gold is plated with only a layer of rhodium 0.05 to 0.5 micrometer thick. Because of this thin plating, cracks will develop causing oxides to form. This will weaken the rhodium coating even more. A good idea is to plate with about 2.0 micrometers of rhodium for longer lasting and more durable jewelry. Replating can be done at your local jeweler.
As stated above, white gold ring sold in the EU may contain some nickel and still conform to the EU Directive on nickel. Sensitised people may find that they react to such jewellery. Conforming to the EU directive is no guarantee that these alloys will not cause an allergic reaction. Check with your retailer that the alloy is nickel-free! Rhodium-plating should provide some limited protection, but remember electroplatings are often porous and will, in time, wear away!
There is currently no legal requirement in many countries for the retailer to tell purchasers if the jewellery is rhodium-plated. This applies to some platinum jewellery as well as white gold. Purchasers should always demand to know if their jewellery is rhodium-plated. If the jewellery is rhodium-plated, then you cannot know how white (or not) is the gold alloy underneath. A good quality white gold, with good colour, should not need to be rhodium-plated but may well be to conform to a consumer expectation.
As palladium white gold is more expensive, there is a demand for cheaper alternatives that are nickel-free. Many new, patented alloys are coming to market, most of which rely on manganese additions as the main whitener. Some are palladium-free and others are low palladium alloys. They tend to be hard and more difficult to process. Many of these alloys are not a good white colour and require rhodium plating. They may suffer cracking and tarnishing problems too. Compositions of such alloys are not published.
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