About Precious Metals

Metals, such as gold, silver, or metals in the platinum-group (such as platinum and palladium), that resist oxidation are known as precious metals. In the industry, these are also known as "Noble" metals, the Middle English term for precious metals.

Precious metals are usually alloyed (combined) with other metals to make them stronger, less pliable and more practical for everyday wear. Here's what you need to know about precious metals used in jewelry:

Gold

Gold's purity is categorized in terms of karats, the standard unit of purity measure for Gold. Pure gold is measured as 24k (karats). However gold in its purest form is too pliable to be practical for everyday wear. So it, like many other precious metals, is alloyed with other metals for strength.

Here are some examples of the most common karat measures used in jewelry:

• 24 karat gold is 99.90% pure
• 18 karat gold contains 75.00% gold (18 carats / 24 carats = .7500)
• 14 karat gold contains 58.33% gold (14 carats / 24 carats = .5833)



Alloying gold can also affect its color, and gold can have a wide variety of finished colors, though yellow gold is the most common. Here are some common examples of gold alloy combinations:

		alloy content percentage
		gold	silver	**copper	zinc	*nickel	palladium
Yellow gold	14k	58.50%	4.00%	31.20%	6.30%
	18k	75.00%	16.00%	9.00%
	22k	91.70%	5.50%	2.80%
White gold	14k	58.50%	0.50%	27.00%	7.00%	7.00%
	18k	75.00%	4.00%	4.00%			17.00%
Red gold	18K	75.00%		25.00%
Rose gold	18K	75.00%	2.75%	22.25%
Pink gold	18K	75.00%	5.00%	20.00%
*	Palladium is sometimes used in lieu of nickel. Both have allergenic properties, so gold alloyed with platinum is a better choice for those who suffer from contact dermatitis.
**	Although less common, copper can also cause allergic reactions in some people. Using alloys with a lesser copper content may help. If not, sterling silver is the better choice.

Further mixturess of gold and other alloys are combined to make other colors less commonly used in jewelry. These include Black Gold, Blue Gold, Green Gold and Grey Gold.

Palladium

• Palladium is 95% pure.
• Palladium is extremely durable in it's pure form.
• Palladium does not need to be alloyed with other metals.
• Palladium is hypoallergenic and very resistant to corrosion and oxidation.
• Palladium is a member of the Platinum-Group of metals.

Platinum

• Platinum is 95% pure and alloyed with 5% other metals, usually other members of the platinum-group metals.
• Platinum is durable but may scratch.
• Platinum does not need to be alloyed with other metals.
• Platinum is hypoallergenic and very resistant to corrosion and oxidation.
• Platinum is a member of the Platinum-Group of metals.

Silver

• Silver is 99.90% pure.
• Sterling silver is an alloy containing 92.50% silver and 7.5% of another metal or metals, most commonly copper.