The purity of gold is designated by karats (kt or k). Don't confuse karats with carats, which is unit of weight used exclusively with gems. Pure gold is 24 karats, but most jewelry is either 14-karat gold, which is 56% gold, and 18-karat gold, which is 75% gold. An alloy must consist predominantly of gold to be marked as karat gold. Anything less than 10k cannot be marked or even considered karat gold.
Yellow gold can be any karatage but the most common in luxury jewelry is 18k gold, which has a rich color but also the strength to last a lifetime. The most common gold alloy used in the United States is 14-karat, which is a little less rich in color.
To give a platinum-like look to gold, manufacturers mix in whiter metals, either nickel or palladium, a platinum group metal. At RockHer we use a palladium alloy because some people are sensitive to nickel. Generally, white gold is also plated with a thin layer of rhodium, a platinum group metal, to make it even whiter. This layer can wear off over time, requiring replating to look new again.
The color of rose gold has a delicate peach tint thanks to the addition of copper to its alloy. Like yellow and white gold, rose gold can be either 18-karat or 14-karat. We especially love its delicate color in contrast to platinum and white gold in two-tone styles.
Platinum is the world’s most precious metal. Amazingly malleable, platinum is durable and holds gems more securely than any other metal. Its strength means platinum jewelry can be delicate yet strong. It’s also very rare: if all the platinum ever mined were melted and poured into a pool, the platinum would barely reach your ankles. One of the most important attributes of platinum is that it is hypoallergenic. If you are at all sensitive to metal against your skin, you should definitely select platinum for your engagement ring, wedding band, and any other jewelry you wear daily. Platinum is one of the densest metals: it has a surprising heft you will notice immediately when you hold a piece of platinum jewelry. Platinum rings weigh about 60% more than the same rings in 14K gold. Many think that the weight of platinum jewelry feels luxurious to wear. Purity standards for platinum are much higher than those for gold. Although the law does not require it, all of our platinum jewelry is made with 950 parts platinum per 1,000--equivalent to 95% purity. Look for a 950 stamp on any platinum jewelry item you are buying to insure that you will benefit from the metal’s hypoallergenic properties.
A platinum group metal, palladium is rare, lustrous, and naturally white. Palladium has the purity and color of platinum but is less dense, making it more affordable. Since palladium isn't as heavy as platinum, it’s a good alternative to platinum for earrings. And just like platinum, palladium jewelry is 95% pure, which means you get more precious metal in your jewelry compared to white gold. Palladium shares platinum’s hypoallergenic qualities. And while much white gold needs rhodium plating to keep it white, palladium is the same color throughout. In fact, palladium is often used in white gold alloys. Much of the palladium on the market was mined in the United Stated at the Stillwater Mine in Montana.
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