I've put together my thoughts on different metals used in jewelry. Rather than put together a really technical document, I am just going to break everything down in basic terms, and add my personal commentary. So basically this in my opinion, but is in no way fact.
I use a Kee Gold and Platinum tester for testing all of my gold and platinum. This includes items that I cast, supplies I purcahse, and any other metals that I buy or sell to ensure that everything is of the grade and purity that it should be. This is a state of the art electronic testing system. Much more reliable than an acid test.
This is just a general term used to describe any metal which is made up of a mixture of two or more metals that have been combined to create a new metal, or a similar metal with different properties. For example: Sterling silver, and 14k gold are both alloys.
Copper is seldom used in jewelry. And there are several good reasons for that. Here are some Pros and Cons:
Pro: It is easy to work with, and cheap. They sell the stuff by the yard at the hardware store... so how expensive can it be?
Con: Even though it is cheap, it will only be a few bucks cheaper than sterling silver. With hand made jewelry, most of the cost is in the labor when dealing with copper or sterling silver.
Pro: It tarnishes. Well, this can be a Con too depending on your thoughts on Tarnish. I use the tarnish as a way to accent my designs. It also means the ring will change colors over its life span. Some people like this, others don't.
Con: it is relatively soft. So while easy to work with, it is also damaged easier.
Pro: Has a great rustic charm, and mixes well with sterling in mixed metal designs.
Con: The can turn your skin green, and with some people, it may cause an allergic reaction.
Bottom line: Buy copper jewelry if you love copper, and the tarnish, green skin and softness doesn't bother you. Don't buy it simply as a cheap replacement to other metals.
Used occasionally in my work, especially on my oxidized designs, since brass does not oxidize nearly as quickly as sterling silver does. An effective way to produce bright yellow accents in mixed metals designs, but seldom, if ever, used as a one-and-only metal for jewelry design.
As a designer, sterling silver is my favorite. It is inexpensive to make mistakes in, it is easy to work with, and it oxidized to pure black so designs are often created to take advantage of this fact.
During the last few years, there has been a steady rise in the number of people who are buying sterling silver not just as fashion jewelry, but for occasion jewelry as well, such as wedding bands and engagement rings.
So what is sterling silver? All sterling silver is required to be 92.5% pure silver, and 7.5% pure copper. Jewelry made out of sterling silver is usually stamped with a ".925" or a Sterling" stamp to indicate its purity.
Pros: Less expensive than gold or other precious metals, it is also the most pure white color of all white precious metals when it is clean. Allergic reactions are rare, but people have been know to have silver turn their fingers black. I have found that this happens for one of several reasons:
A. You buy a cheap ring from (A country that shall not be named, but lets just say that a lot of cheap stuff comes from there) and it is not actually sterling silver. Who knows what it is made of...
B. The ring is in fact sterling silver, and you are one of a lucky select few who are either allergic to silver, or are so allergic to copper, that the small amount found in the alloy causes a reaction. Although generally this results in a skin rash, not in a black mark.
C. Everyone has oil on their skin. People also wear lotions, body sprays, etc. Sometimes, some odd combination of your particular body PH and/or the lotion your wearing, bug spray etc... can react with the silver to produce a black ring on your finger.
Cons: Not quite as durable as gold or platinum. It is also harder to maintain a good polish or special finish such as a matte finish since the material is softer. Expect to polish it regularly if you want to ward off tarnish.
Bottom line: Buy sterling silver if you don't mind a bit of extra maintenance and if budget is a concern.
What is a karat? Is it the same as a carat? No. Carats are a unit of measurement for weight. Specifically used in the diamond and gemstone industry to weight out, size and price stones. A carat has nothing to do with gold.
Karats, are a system of purity, used in gold alloys. A 14k gold ring (14 karat) is made up of 14 parts pure gold and 10 parts other metals. The total is 24 parts.
An 18k gold ring is 18 parts pure gold and just 6 parts other metals. The total is also 24 parts. Sensing a pattern?
So by that logic, 24k gold is another way of saying pure gold! Although 24k gold is very rarely used in jewelry since it is very soft.
So what are these other metals? It varies from company to company, and it also depends on the color of gold being made. It should be noted that yellow gold, is the only color of gold that exists in nature. All other colors of gold have to be created, by man, by alloying the yellow gold with other metals to change its color. So in that sense, there is no such thing as "pure white gold".
White gold, is usually made by mixing gold with silver, nickel, platinum, palladium, or some other white metal. But those are the most common. The lower the karat of the gold, the more white metal is introduced. So as you can imagine, 18k white gold, which still, by law, needs to have 18 parts out of 24 be pure yellow gold, will only have 6 other parts (25%) of its mass made with white metals. So naturally it will have a subtly yellow/grey tinge. 14k white gold actually has a lot more white metal used in it so it is actually a lot more white, than 18k white gold. So if you are opting for white gold, there is no point in getting 18k unless you want the ring to have a more grey appearance (Looks great for mixed metal design with sterling silver, or men's rings!)
The same is true of rose gold (often called pink gold). The lower the karat of the gold, the redder the alloy will be, 10k rose gold usually being the most rose colored, and 18k rose gold, usually being more of a yellow/rose hue.
So why opt for gold? Well, it has pretty much been the most popular metal for jewelry since the beginning of time for a good reason: It lasts a long time. It is tarnish resistant. It requires less maintenance, and it is also resistant to most chemicals, acids and other things which can advance the age of other metals.
Gold is also pretty easy to work in. It is not hard to mix two different colors of gold in the same project and it also plays well with sterling silver.
Bottom line: Chose gold if you want the ring to last a long time, and if you don't want to have to polish and remove tarnish every so often.
Rhodium is a relatively new player in the line up of metals used in jewelry. Most people have never heard of it, and yet most everyone has seen it and almost anyone wearing a white gold ring, is actually wearing a white gold ring which has been plated in rhodium!
Rhodium is very expensive. I am yet to actually see a ring made entirely from rhodium. But in recent years, it has become common practice to plate all white gold jewelry with rhodium. In fact, some jewelers would go so far as to say that it NEEDS to be done. to this I say Poppycosh!
Reasoning: White gold, as I mentioned above in the section about gold, is actually a subtle grey color. It still looks pretty white when polished, but not as bright white as rhodium. Don't believe me? Next time you are in a jewelry store, as to see the white gold engagement rings. Then ask if they are rhodium plated. I'll bet my left shoe the answer is yes. Unless... You are in my shop!
I don't rhodium plate my jewelry. Rhodium is advertised as a very hard metal. And true enough, it is very hard. But it is just a plated surface. Plating is a process in which a micro thin layer of metal is added to the outside of a finished piece. So what happens over time? The same thing as with any plated jewelry. The plating wears off. From, what I have heard, the average person will need to have their ring re-plated every 1-3 years. Its expensive to do so, and it usually means parting with your ring for a week or two.
So why do all these jewelers seem to not only offer it, but make it mandatory? Bottom line: It adds to their bottom line. Not only does it raise the cost of a piece, but the piece is also going to be re-plated every so often which means that if they get to do the service work, they'll get paid for that too. Plus it makes everything super shiny and sparkly. Not really my style.
Another disadvantage is that making mixed metal pieces (Which I love to do) becomes virtually impossible.
So an important note: If you are buying a white gold ring from me to match a white gold ring that you already have: Find out if yours is rhodium plated. If it is, you'll have to have the ring I make you plated also if you want them to match. I can have this done for you if you need, but it is not something that I automatically turn to.
Platinum is a great metal for more intricate designs. It is strong, and also more ductile than gold or silver, meaning that it can be made into more intricate shapes and designs. It is also very durable over the long run. The main reason for this is that platinum does not wear away the way that gold or silver does. Instead of scratching, the metal is just displaced. This is one reason why it is a lot easier to find a vintage platinum ring rather than a vintage silver or gold ring. Over time a platinum ring is more likely to get a little more smushed and rounder, but less likely to lose a stone due to a prong getting broken off or slowly worn down. For these reasons (plus the fact that it is typically three times more expensive that 14k gold) it is often chosen for special rings, like anniversary bands or wedding sets.
Another advantage, (or disadvantage) is that it is a lot denser than gold. So a tiny dainty ladies ring will have a bit more heft to it. A men's ring will also be a lot heavier. For this reason, you don't see a lot of men's rings made in platinum.
Also a new-comer on the jewelry market. Previously used in computer and aerospace parts, palladium is now being used in men's rings in stores all over the country. It has a new exotic sound and it is also lighter than gold (having roughly the same density of silver) and is also less expensive per ounce. The only drawback is that it is a lot harder to work with than any of the other commonly used metals, being more brittle and also being harder to find suppliers who carry raw materials.
Ultimatly, it does make a very attractive metal for mens bands. It is very durable and has a soft grey/white luster. It is similar in cost to 14k or 18k gold, depending on current gold prices.