Precious Metals Used in Jewelry: All that Glitters…
All that glitters is definitely not gold. It might be fake gold over aluminum or copper, it might be gold, or it might be some gold-colored metal and totally worthless. How can you know and what does it all mean? Stick with me here, and we’ll get a little knowledge, which makes you a powerful buyer.
Gold—Au—A metallic element with low reactivity, low melting point, low hardness, high malleability, high density and a bright yellow color. Since gold is very soft, it is alloyed or mixed with other metals to harden it. From these mixtures we get varying amounts of purity often described in karats.
Fine Gold=Pure Gold=24k Gold=999 ppm=99.9% Gold
Fine Gold is the most purely refined gold on the market but it has drawbacks. It is very expensive, and it is too soft to be of any real use in most jewelry. Surprisingly, it can cause allergic reactions (see my article on contact dermatitis.) Karat is used to denote how much gold is contained in the metal, with 24k being the highest or purest. Karat with a k is used to indicate the maximum amount of gold in a piece, whereas carat with a little c is a weight measurement used for diamonds and colored gemstones. Parts Per Million (ppm) can also be used instead of karat, and in 24k gold, 999 is analogous to saying that something is 99.9% pure gold.
Alloyed Gold=22k, 18k, 14k, 10k Gold=Colored Gold (White Gold, Rose Gold, Green Gold, and other colors)
Alloyed gold, or anything less than 24k gold, has varying amounts of gold mixed or alloyed with other minerals which can include copper, silver, nickel, zinc, and chemical grain refiners and deoxidizers such as silicon and boron. The higher the karat count (22k being more than 10k) is (or parts per million stamp,) the more gold is present and the less base metals and hardeners are added to the alloy. White gold is simply gold mixed with silver and possibly other metals, depending on the manufacturer.
Silver—Ag—A metallic element with low reactivity, low melting point, low hardness, high malleability, high density and a silver color.
Fine Silver=Pure Silver=999 ppm=99.9% Silver
Fine Silver is harder than gold but still soft enough to work in jewelry. It has the advantage over gold in that to date there are no known cases of allergic reaction to pure or fine silver. Taking a fine polish, fine silver is an excellent jewelry choice for many reasons, not the least of which is that it is beautiful but much more inexpensive than gold alloys.
Alloyed Silver=Sterling Silver=925 ppm=92.5% Silver
Sterling Silver is harder and more durable than pure silver, but the remainder of the mixture can be made up of copper, zinc, nickel, and other base metals, depending on the refiner. In the case of Argentium Silver, the metalloid Germanium (Ge) is added instead of nickel or zinc. Non-nickel sterling is safe for jewelry, and is a good choice for most jewelry applications because it wears well and is inexpensive.
Platinum—Pt—A metallic element with low reactivity, fairly low melting point, good hardness, high malleability, high density and a whitish silver color. Platinum is a very expensive metal but often used in jewelry because of its hardness. There is, however, good evidence that the body’s sweat may react with this metal to contribute to contact dermatitis and jewelry rashes.
Titanium—Ti—A metallic element with very low reactivity, very high melting point, extreme hardness, low malleability, high density and a grayish silver color. Titanium is perhaps the best choice of metal for jewelry since it does not react with the body to cause contact dermatitis or jewelry rashes (see my article.) It is very light in weight (unlike platinum, silver and gold which are very heavy for their weight, or dense) and unbelievably strong. Used for rockets and spaceships because it is so feather-light, this metal can be expensive in large quantities, but for smaller scale objects such as jewelry it is relatively cheap.
Niobium—Nb—A metallic element with very low reactivity, high melting point, extreme hardness, good malleability, high density and a dark silver color. More easily worked and polished than titanium, niobium is also an excellent choice for jewelry because of its lightness and strength, and its affordability. It is also one of the very few metals (along with titanium, rhodium and argentium) that do not cause contact dermatitis or jewelry rashes.
Rhodium—Rh—Another metallic element, which is often used as a coating for more metals that may tarnish such as silver, or softer metals such as gold. Rhodium is also so rare as to be prohibitively expensive for the bulk of jewelry-making.
Palladium—Pd—Another metallic element, which, like Rhodium, is often used as a coating for more metals that may tarnish such as silver, or softer metals such as gold. Rhodium is also so rare as to be prohibitively expensive for the bulk of jewelry-making.
Ruthenium, Iridium, Molybdenum, and Tungsten—Metals which can also be used as alloys but which (with the exception of tungsten) are not really practical for jewelry use.
Nickel, Copper, Zinc, Aluminum, Cobalt, Chromium, Tin, and Iron are all base metals which are used with precious metals or in combination with each other to make various alloys. Because of their reactivity with the body, most of these are either toxic, or can lead to rashes, irritation, or contact dermatitis and so are not recommended for jewelry.
German Silver—Not silver at all, but a low silver-content alloy, usually made of 60% copper, 20% nickel and 20% zinc. The high nickel content (and so high potential for allergic reaction) makes it unsuitable for jewelry.
Stainless Steel—An alloy of iron, and at least 10% chromium (which can cause jewelry rashes in many people) as well as the allergenic trouble-maker, nickel, and the remainder will be made up of carbon and any number of other base metals, depending on the type of steel. “Surgical steel,” a term used to market supposedly allergy and irritation-free ear wires and posts, is nothing but regular steel with additions of nickel, chromium, and molybdenum. Because of these additions (notably nickel,) surgical steel can cause jewelry rash and skin problems for many people, both in piercings and other applications. The term surgical steel merely means that this steel doesn’t rust, and is therefore good for surgical instruments, but this does not mean that it is irritant or allergy-free when in constant contact with the skin.
Bronze—Another alloy containing copper, arsenic, phosphorus, aluminum, manganese, silicon and possibly nickel and not recommended for jewelry.
Brass—An alloy containing copper and zinc and not recommended for jewelry.
Gold Plated—Not gold, but made with a process by which a microscopically thin layer of gold is electroplated onto silver or copper, most often with a layer of zinc or nickel in between. Although most costume jewelry is made with gold-plating, it really isn’t suitable for jewelry since the layer of gold will be diffused by the base layer and results in fading, tarnishing, or can expose the wearer to the nickel layer causing allergic reactions and rashes. Gold plating is usually easy to spot because its weight, compared to solid gold, even an alloy, is quite light.
Gold Filled—Not gold either, but made when a slightly thicker layer of gold is bonded by heat and pressure to an underlayment of brass. Not suitable for jewelry since the layer of gold will wear away eventually and can cause the rashes associated with gold-plated jewelry. Depending on widely fluctuating manufacturing standards, gold-filled items may contain very little actual gold while still being sold at a much higher price.
Fakes and Tricks—Caveat Emptor translates as “buyer beware” and it simply means that if you see a gold piece in an antique shop, auction, or market, and the price is too good to be true … it probably is, a fake, that is. The metal most often faked is gold, since it is the most expensive and can bring the highest prices.
Watch carefully for weight, since hallmarks and stamps can be fraudulent (although it is illegal—but hey, if a seller is passing fake gold, what’s one more fraud?) A good rule of thumb is to compare the supposed gold with what you know to be solid gold (a wedding ring, for example) and heft the two items in each hand to test their relative weight to size. Because of its density (gold atoms are packed much tighter and closer than other metallic elements) real, solid gold will be very heavy for its size. You can also look at color, and if a piece is unnaturally yellow (again, it helps to have something real to compare) or is a different shade (like a reddish gold) then you know it is at least an alloy (probably having copper or another metal added) and you can bargain accordingly.
Also look at the shine. Real, solid gold has a very mellow glint and is not overly sparkly, so be suspicious of gold that is incredibly shiny. This shine probably indicates a coating of some other metal overlay (or simply a gold-filled piece.) Further, you can look at the manufacture. If a piece is round, and quite light, there is a good chance that it is hollow, or rolled gold. If the gold itself is real, and the price is low, this is not a problem, but look carefully for higher-priced items whose weight does not indicate a solid gold piece. Rolled gold can also be overlayed on top of heavier metals such as silver, copper, or even lead.
These tricks are as old as gold ornament manufacture (which is thousands of years old,) and not at all limited to modern times. Many foreign markets are flooded with fakes and it is up to you as the buyer to make sure that you properly vet and investigate your jeweler or seller, weigh the quality and price, and decide for yourself whether you are paying what you should and getting what you want.