What You Should Know About Silver and Gold
The precious metals used in jewelry are gold, silver and platinum. They are very alluring with a powerful combination of color, luster and heft. Often, the first thing you notice about jewelry is the way it shines and reflects light. Understanding a little bit about how jewelry is made will make you a more informed consumer.
Alloys Make the Difference in Look and Workability
Alloys are other metals that are mixed with silver or gold to make them better for jewelry. This is done to make the precious metal more workable, to improve the appearance or change the color, or to make the jewelry more affordable. The most commonly used alloys in jewelry are copper, zinc and nickel.
Standards and Purity
Believe it or not, standards governing the use of precious metals go back to ancient Egypt and Rome. Gold and silver were carefully weighed, with official marks being used to indicate purity. All of Europe adopted quality marks in the 14th century and in England, guilds were established by the King to test and mark the purity of precious metals.
Today, standards governing the use of silver and gold are very stringent, but they do vary quite a bit from country to country. U.S. Federal Trade Commission regulations do not require a karat stamp on gold jewelry. However, if U.S. gold jewelry is stamped, it must also bear a company trademark. This is also true of platinum and silver items.
Fineness means the purity of the metal or how much precious metal is present. Metal content is often stated in terms of parts per thousand (ppt) and by weight. Some countries, such as the U.S., also describe gold in terms of karatage, with one karat being 1/24 of the total purity of gold. Karat gold cannot be lower than 10K in the U.S. to be called gold.
By the way, do not confuse "karat" with "carat"; they are not the same terms. Karat refers to gold ONLY; carat refers to gem weight as in diamonds. K or Kt is the abbreviation for karat.
Pure polished silver shines more brightly than all other metals, reflecting 90% of visible light back to the eye. Pure silver is often considered too soft for functional use in jewelry, so an alloy must be added.
Sterling silver is a mixture of 925 parts silver to 75 parts copper (for hardness). Due to differing body chemistries, sterling silver will tarnish on some people and not on others. Sterling silver is very often plated with another metal, like rhodium, to protect the sterling and keep it from tarnishing.
Silver plate is a layer of silver over a base metal (like brass). In the U.S., you cannot use the mark "silver" or call it "sterling" if it is actually plated.
Like silver, gold is rated by its degree of purity. The karat weight of gold is measured against the standard of 24 karat gold (pure gold). Therefore, 22 karat gold would have a purity of 22/24 or 91.7 percent, 18 karat gold would have a purity of 18/24 or 75 percent, 14 karat gold would have a purity of 14/24 or 58 percent and 10 karat gold would have a purity of 10/24 or 41.6 percent. The higher karat weight a gold piece of jewelry has, the more valuable that piece of jewelry will be.
As the purity of gold decreases, the alloy in the jewelry increases. Copper and silver are the most common alloys used when making gold jewelry and white gold is usually made with a nickel alloy.
Nothing less than 10-karat gold can be legally marked or sold as gold jewelry in the United States. The legal requirements for minimum gold content vary widely country-by-country (e.g., 9K is popular in Britain, while in France, Italy and Switzerland, 18K is the lowest permissible standard to be called gold).
In many instances, the gold product will be marked by karat weight. If not, the piece might be:
- Vermeil - Vermeil is Sterling Silver plated with 10K gold (or better) that is a minimum of 2.5 microns thick.
- Gold Plated - Gold Plated (GP or KGP or RGP) items have a very thin layer (a minimum of 0.5 micron) of gold electroplated to the surface of the item. They have some other type of (base) metal underneath. GP items are always less expensive than their Gold Filled counterparts.
- Gold Filled - Gold Filled (GF or KGF) is a layer of 10Kt or finer gold mechanically bonded under heat & pressure to one or more surfaces of supporting base metal, then rolled or drawn to a given thickness. The plating must be at least 1/20 of the total metal weight. The amount of real gold used is why GF items are always much more expensive than their gold plated counterparts.
Precious Metals by the Numbers
|Karatage||Parts/Gold||Percent Pure Gold||Fineness (European marking)|
|14K||14/24||58.33||583 sometimes listed as 585|
925 Sterling Silver - 92.5% pure silver
958 Britannia Silver - 95.8% fine, represented by a lion's head or the seated figure of Britannia.
950 Platinum - 950ppt or more of pure platinum may carry the mark platinum, plat. or pt.
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