PART 1 – THE PRECIOUS METALS
The holidays are fast approaching and this is the time of year when lots of people will (hopefully) be buying lots of jewelry. But it can be a little confusing as to what you are buying especially when it comes to metals-there are many kinds used in jewelry! So here is a list of the most common ones and some of their properties. It’s not an exhaustive list but it should help clear up some confusion…let’s start with the easy ones…
World’s Largest Gold Bar
Gold is an element, and its symbol on the Periodic Table is Au (from the Latin name Aurum), and is of course known for its bright yellow color. It is considered a precious metal, as it is valuable and highly sought after…and expensive! The price fluctuates daily but as of this writing, gold is $1227.50 per troy ounce (one troy ounce = 1.10 ounces = 31.103 grams). While I was looking up gold in Wikipedia I learned an interesting bit of trivia…”Most of the Earth’s gold probably lies at its core, the metal’s high density having made it sink there in the planet’s youth. Virtually all discovered gold is considered to have been deposited later by meteorites that contained the element.” Wow, who knew…so that means people are walking around with extra-terrestrial jewelry…that’s pretty cool.
So when you look at gold jewelry you hear words like ’14 karat’ and ’24 karat’ gold…here’s what it means. 24 karat gold is pure 100% gold. Because gold is such a soft metal, as well as expensive, you mostly see 14 karat gold, which is an alloy of 14 parts gold to 10 parts other metals (58.7% gold). This makes the product a little harder and more durable. And affordable.
I don’t work a lot with gold because it is so expensive, but sometimes use it for a process called keum-boo, which is pure gold leaf bonded to pure silver. It’s actually quite easy…you take a piece of fine silver, heat it to 500-700 degrees (I use a hot plate), add a piece of 24k gold foil and use a metal or stone burnisher to rub it on the surface of the silver, where it will chemically bond. If you are interested in the process, artist Celie Fago has an excellent book on it…you can check it out here.
Here is an example of some keum-boo I did on some fine silver leaves I made….they sold last year and I really should make another pair as they as so pretty.
Fine silver leaf earrings with 24k gold accents
What is white gold? It is an alloy of gold and at least one white metal, usually nickel, manganese or palladium. Its purity is also measured by karats. Rose gold (also known as pink gold and red gold) is an alloy of gold and copper…the higher the copper content, the more pronounced is the red color. A common alloy for rose gold is 75% gold, 25% copper. Red gold is a 50/50 mix of gold and copper.
OK, silver is clearly my favorite metal…I love its bright white reflectiveness, its relative affordability, and it’s pretty easy to work with. Although silver is much much cheaper than gold (silver is $19.36 a troy ounce as of this writing), its price does tend to fluctuate quite a lot, as you can see from this chart I took from the Rio Grande website (this is where I buy pretty much all my metals and everything else-they are awesome!).
Silver prices 2010-2013
As you can see, it was up to almost $50 a troy ounce in spring 2011! It sucks for us jewelers when the price spikes like that…we have to raise our prices to compensate or we lose money.
Pure silver is also an element, and its symbol on the Periodic Table is Ag (from the Latin argentum) and it also possesses the highest electrical conductivity of any metal (a question I once embarrassingly got wrong while playing trivia-I thought it was copper). Almost all silver used these days is recycled or recovered as a by-product of gold, lead, copper or zinc refining. Besides being used for jewelry, it has tons of other industrial and even medical uses. Interesting bit of trivia…a bill passed in March 2012 makes silver (and gold) legal tender in the state of Utah.
There are several types of silver that I work with…sterling silver, fine silver and argentium silver.
Sterling silver is 92.5% pure silver and 7.5% copper, which is why you see sterling silver stamped with 925. It is pretty much the standard silver you will find in most jewelry, as it is harder than fine silver. Because of the presence of copper in sterling silver, it does tarnish more readily than fine silver and is a little more difficult to work with than fine silver. This is because when you heat it up, you get what’s called firescale, which is a red, purple or blackish stain on that appears on the surface. This is from the reaction of oxygen with the copper in the alloy when it is heated…this also what happens when your jewelry tarnishes, albeit at a slower rate.
Also, because of the presence of copper in the alloy, even sterling silver can turn your skin green, especially if you are wearing a wide ring band on your finger. It’s harmless and is caused by the chemical reaction between the acids of your skin and the metal. The best way to avoid this happening is to try to keep lotions, soaps and other chemicals away from your rings, and remove them before bathing or swimming, particularly in salt water.
I love sterling silver though, as it is fun to work with and beautiful to look at. It makes lovely strong, durable ring bands and chains. I work with it in wire and sheet form and also in clay form (which is what I use to make my sterling silver Leaf Ring).
I will cover Precious Metal Clays in a future blog post but here is a picture of fine silver and sterling silver clays.
Fine silver is 99.9% pure silver (I have no idea what the other 0.1 is). It is slightly whiter and softer than sterling silver and tarnishes less readily than sterling. Because it is pure silver, you don’t get firescale when you heat it, and you can actually fuse it without using solder! If you are interested in doing this to make jewelry (this is how I got started making rings) there is a great book called Silver Wire Fusing that explains it all step by step. You can get it on Amazon here…I highly recommend it.
I work with fine silver in wire form (to make rings), and as Precious Metal Clay…an example of this are my fine silver Leaf Earrings.
Argentium silver is a new form of silver, created in the 1990′s…to make it they have modified the traditional alloy of sterling (92.5% silver + 7.5% copper) and replaced some of the copper with the element germanium (not the geranium flower!). Because it contains at least 92.5% silver, it is still referred to as sterling silver.
The advantages of Argentium silver are that it does not get firescale when heated, and it can be fused without solder like fine silver, and it tarnishes less readily than traditional sterling silver. It is slightly more expensive than sterling silver, and I sometimes like using it for ring bands as it is a little easier to solder.
Although I love platinum, I don’t work with it for reasons I will describe in a minute, but it’s worth mentioning as it is a commonly used metal for jewelry. Like gold and silver, it is an element and its symbol on the Periodic Table is Pt, from the Spanish platina, which translates to “little silver”.
Platinum is more expensive than gold ($1364 per troy ounce as of this writing), as it is one of the rarest elements in the Earth’s crust. Only a few thousand kilograms are produced annually. It is also the least reactive metal, and extremely resistant to corrosion, which makes it valuable for many industrial uses. It is slightly harder than pure iron.
Why don’t I work with platinum? Well, besides being crazy expensive, it has a crazy high melting point which makes it very difficult to work with. Here’s a little comparison…
SILVER 1763° F (962° C)
GOLD 1948°F (1064° C)
PLATINUM 3215° F (1768° C)
Twice as high as silver! But I love the color of platinum and wish I had the skills and tools (and the money) to work with it…
Rhodium is closely related to platinum and like platinum, is rare and expensive. I mention it here because it is also used in jewelry, but almost always as electroplating over white gold and platinum to give it a more reflective, whiter surface, and on sterling silver to protect against tarnish. You almost never see solid rhodium jewelry, not so much because of its cost, but because it not only has a higher melting point than platinum (3565° F!), it is not very malleable at all so it makes jewelry hard to fabricate.
I hope this helped! I know it can get confusing out there, and it’s hard to know exactly what you’re buying. Next time I will cover some very common, less expensive jewelry metals (what they call base metals), which are copper, brass and nickel or german silver. Feel free to let me know in the comments sections if you have any questions, and I’ll do my best to answer them!