Wednesday, September 14, 2011

Engineer's Guide to Wedding Band Metals

J has been researching metal options for his wedding band. Since he is so sweet, he has written up an article based on his research for Posh Purpose. I proofread a bit, but mostly left his words intact meaning this is probably man-friendly. I hope y'all find the info helpful! And remember, this is just a summary of common band metals and their qualities; it is up to you to choose which is best according to your own situation and preferences.

The Engineer's Guide to Wedding Band Metals

In order to choose the metal for your wedding band, you need to determine what characteristics you want in your wedding band. There is no best metal. Everything has trade offs. I'll give a breakdown of each of the more commonly used metals followed by a quick score sheet that gives density, hardness and price.

The density is given as g/cc, and for reference water is 1.0 g/cc. Density is defined as the mass per unit volume, which means how much the ring will weigh for a given size. Some people associate more value with heavier things, other people prefer to not notice that they are wearing the jewelry. You’ll have to try the ring on to know how it actually feels.

Hardness for the purposes of jewelry can be seen as scratch resistance; harder metals do not scratch as easily. However, harder materials are also more brittle. A harder ring won’t scratch, but it’s more likely to chip (and in some cases shatter). Also, harder materials are more difficult to work with, which will often times make the jewelry more expensive. The hardness is given in terms of the Mohs scale, which I’ve only ever seen used on jewelry. Diamond is the hardest material (except, of course, hyperdiamond) with a Mohs hardness of 10.
As with anything, you'll be able to find a wide range of prices, so I'm just going to give a qualitative score. For many of the simple designs, you’ll be able to find much cheaper prices on the internet than in stores. But if the ring you are going to buy represents a considerable amount of money to you, I would recommend going into the store to make sure that you are satisfied with it. For me peace of mind is worth the extra 10-20% I spend.

Gold is historically the most precious metal, and it's major differentiating factor is its color. However it seems to me that yellow gold is largely out of style right now, (but don't put any weight in my observations) making white gold popular. However white gold is white because it's alloyed usually with nickel, which means that people with certain allergies can't wear it. Gold is a relatively dense, very soft and stable metal which means it's easy to form and scratch but hard to tarnish (chlorine at high temperatures does the trick). When you buy gold, you are told its purity in karats, which is a weird and arbitrary scale that clearly outdates the metric system. It's out of 24 karats, so 10 karat gold is 10 parts gold and 14 parts other things. The lower the purity, the harder the metal is, but also the less gold it contains. I always go for low karats because it's more durable and cheaper and most people can't tell the difference by looking at it, but I also like shopping at Walmart.

24K Gold - Density-19.3, Mohs-2.5, Price-$$

10K Gold - Density-13.9, Mohs-3.0, Price-$$

Platinum is popular partially because it's the most expensive metal available. I would say that in general people get it simply because it’s expensive. Platinum is expensive because it is rare and has a lot of industrial applications, but it’s special characteristics make it a very interesting choice. The first thing you’ll notice is that platinum is dense, more dense than depleted uranium. The only naturally occurring elements that are more dense are osmium and iridium. It’s also a pretty tough metal, almost as strong as steel. It doesn’t tarnish, but it gets small surface scratches which make it less shiny. Platinum is not as easy to form as gold, which may somewhat substantiate the fact that platinum jewelry costs so much more than gold jewelry, but I think that it’s most likely just a product of marketing and supply & demand.

Platinum - Density-21.5, Mohs-4.25, Price-$$$

Silver is not a very common choice for wedding bands. I figure a lot of this is because it tarnishes easily. It also is as soft as gold. However, when it is taken care of, it has the potential to be pretty much the shiniest of all metals. It is significantly lighter and cheaper than the above listed options, but I wouldn’t really recommend it. Choosing a silver wedding band is choosing high maintenance jewelry, and let’s be honest, you’re already adding a wife that you have to pay attention to.

Silver - Density-10.5, Mohs-2.5, Price-$

Palladium is an interesting option. It is very similar to platinum (in the same family of metals), but a lot cheaper. It’s also lighter, harder and more abundant. As mentioned earlier, harder metals also means more brittle, which means that even though palladium is harder to scratch than platinum, it’s easier to chip. Palladium is also slightly harder to cast than platinum, which may affect the pricing/availability. I have a feeling though that the main reason that platinum is easier to find than palladium is because jewelry stores want to make more money.

Palladium - Density-12, Mohs-5, Price-$$

Tungsten Carbide
Tungsten carbide is a particularly interesting choice for me as an engineer. Tungsten has a ridiculously high melting point, and is extremely hard. It is hard enough to be used as a cutting tool for hardened steel. Tungsten carbide is harder than most gemstones, with only corundum (sapphire) and diamond being harder. This means that you would have to go out of your way to scratch it (like rubbing it with a diamond file) so it will look brand new years after you buy it. It’s impossible to resize, and you can chip and even shatter it if you aren’t careful. Because of its hardness and high melting point, once it’s damaged or your finger grows, it’s done. If you are the sentimental type who wants to keep the same ring forever then this may not be the choice for you. Compared to the precious metals, a tungsten ring is quite cheap. There is a tungsten alloy which has a very cool blue tint to it, but I believe it’s from the presence of cobalt. I’m sure the state of California thinks this alloy is a carcinogen.

Tungsten - Density-15.8, Mohs-9, Price-$

Titanium is an extremely strong and lightweight material. The density of titanium is about ⅕ of the density of platinum. If you want a ring that you can’t feel, titanium may be a good option for you. It’s going to be pretty hard to resize, and it doesn’t have a very jewelry-like appearance. Since it’s on the harder side, it’s more likely to chip, but it’s not so hard that it will resist scratching. It’s not a very shiny material anyways, so any scratching will be less noticeable.

Titanium - Density-4.5, Mohs-6, Price-$

Stainless Steel
If you are seriously considering a stainless steel wedding band, more power to you. However, you should know that most people generally think this metal has a cheap look to it - think cubic zirconia. Stainless steel is not particularly dense when you’re comparing it to precious metals and not particularly shiny or scratch resistant. A stainless steel band is the wifebeater (t-shirt, not abuser) of wedding bands; it does not look classy and does not have good functionality.

Stainless Steel - Density-8.0, Mohs-4.5, Price-$