Science

A Peridot is Forever

As a geologist and a skepchick, I’d like to debunk a popular myth: a diamond is not forever. This clever phrase was coined in 1948 as a marketing slogan for DeBeers, but I cry that it’s false advertising. Diamonds, formed at high-pressures deep within the Earth, are metastable in the low pressures at Earth’s surface. Over a few million years, the carbon atoms in the gemstones will rearrange, converting the diamonds into graphite. Pencil lead, essentially.

A real forever gemstone? Maybe zircon. There are zircons in places such as western Australia that are over four billion years old. Forever is a long time, though, and even zircons eventually degrade. Blue zircons can make really beautiful gemstones, though.

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Okay, so maybe I am being too picky; perhaps I’m too much of a geochemical snob. On human timescales, diamonds appear to last forever. To prove a point, though, if I if ever became engaged, I want a peridot ring. Peridots are not forever gemstones. Actually, peridot is one of the most ephemeral gemstones. Peridot is essentially olivine, which is the first mineral to weather in a rock containing this mineral. Olivine weathers quickly because the weak metallic bonds holding together isolated silicate tetrahedron are easily broken down by physical and chemical weathering.

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But I like peridots much better than diamonds becaue they’re a beautiful green color, and they remind me of some of my favorite volcanoes, where peridots can be found. Sure, peridot is not as expensive as diamond, but I personally think that the diamonds are overrated. Diamonds, with the possible exception of rare colored diamonds, are not worth what most people pay for them.

Diamonds are somewhat common, actually, and the market for the traditional off-the-shelf diamond engagement ring is artificially controlled. The economist might argue with me. Items are worth whatever people will pay for them. However, geologically, I just don’t see it. I highly recommend the book Diamond: A Journey into the Heart of an Obsession by Matthew Hart for anyone wanting to learn more about diamonds and the diamond industry. This book is an excellent quick read for anyone wanting some evidence that that diamonds are not really worth that much.

And I wonder: why all the hype about diamonds when there are so many other gemstones? Why should everyone have diamond engagement rings? Why can’t some people have zircons or sapphires or peridots, if they want to? Why is it “odd” (in the words of my grandmother) to have anything other than diamond?

Certainly, love and marriage are even more ephemeral than these gemstones, even highly-degradable olivine. These days, the typical marriage is lucky to last five years, so what does it matter which gemstone symbolizes your bond? Any gemstone is likely to last longer than your love. Peridot, one of the shortest-lasting gemstones (degrading in hundreds to thousands of years, in most cases), and diamond, one of the longest-lasting (degrading in millions of years), both will last much longer than the average or even the extraordinary marriage. Even if one is lucky and is married for sixty years or more, that peridot gem should still be going strong.

So, why diamonds? On human timescales they aren’t any longer-lasting than other gemstones, and they’re not particularly rare or valuable. I mean, how rare can they be when every young, engaged female has one around her finger?

Yet even my geologist friends, who appreciate the worth (or lack of worth) of diamonds, have diamond rings on their fingers or purchase diamond rings for their fiancees. I guess that so-called tradition might have something to do with it. A girl wants the diamond engagement ring, just as her mother and gradmother had. But are diamond engagement rings really traditional? Not everywhere, certainly. Diamond engagement rings are starting to catch on even in places such as Japan and China, where these rings certainly are not traditional. Why? Clever marketing, in my opinion.

Just a few days ago, a good friend of mine became engaged. Of course, she sent me digital photographs of the diamond engagement ring. I am quite happy for my friend. She’s marrying a great person, and she was so happy on the phone. I told her, quite honestly, that her ring is beautiful. I may not understand why a diamond ring is so important and necessary for an engagement, but I do understand why this ring is so important for my friend and why she is so proud to display it on her finger.
I wouldn’t begrudge her happiness nor the engagement ring she’s been dreaming of for years.

But for me, if I ever decide that it’s time to be married? Peridot. Or maybe zircon… or zoisite… or maybe alexandrite. No, peridot it is. Or maybe blue zircon… oh, I can’t make up my mind. Okay, peridot and blue zircon. But diamond? How conventional and boring!

Evelyn

Evelyn is a geologist, writer, traveler, and skeptic residing in Cape Town, South Africa with frequent trips back to the US for work. She has two adorable cats; enjoys hiking, rock climbing, and kayaking; and has a very large rock collection. You can follow her on twitter @GeoEvelyn. She also writes a geology blog called Georneys.

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28 Comments

  1. I've always found vividly colored gemstones more fascinating and appealing than relatively colorless diamonds as well.

    It amazes me how tiny amounts of metals and other elements can combine in such spectacular ways. Of course it takes a skilled gemcutter to shape and finish a stone so its visual appeal is maximized. But it tickles me that the laws of physics and chemistry allow such beauty, and that we can percieve it.

    The universe really is a visual treat in all its aspects.

  2. As far as turning it into jewelry is concerned, diamond does have one advantage over almost all other gems: It's very high index of refraction. This means that if you cut it very well, a normally colorless diamond can shine with a rainbow of colors. Now, these diamonds are worth it…

    But wait! I said "almost all other gems." There's one gem with an even higher index of refraction than diamond, and it's that pretender to the throne: Cubic Zirconium. So, finely cut CZ will appear even more beautiful than finely cut diamond. Of course, they're not "natural," so people still think diamonds are somehow better.

    Ugh, don't get me started on the craze over "natural"…

  3. Hang on– So Cubic Zirconium outlasts diamond? Cool! I always like the way a stone looks, as opposed to the vanity value of it. Alas, I'm not so enlightened that I wuold be comfortable wearing a poor icky fake diamond.

    Fortunately, diamonds are not my favourite stone. I have a penchant for Lapis Lazuli. Deep, rich blue, with those veins of gold running through it….

    If I may ask, How is Lapis formed? What gives it those colours?

  4. Yes, you can find peridot rings, although when I checked (around Valentines day) I found many gold rings which also had diamonds in them and just used the peridot to give some colour. But most of them also had really ugly settings. And still they were insanely expensive (as in: one months paycheck, as engagement rings tend to go).

    The nicest peridot ring I found was only about $30 I think. A very simple silver-coloured design. So peridot is relatively cheap AND readily available, although for an engagement ring you'd probably be better off having something custom made.

  5. The way to do it is to have a ring custom-made by an artist with whatever stones you like. If you're going to drop a load of money, it might as well be spent on something unique instead of on a boring diamond. And let's not even get started on the blood diamond problem…

  6. My very favorite part of a natural history museum is always the rock section. I love all the different shapes and colors of rocks, and I don’t see anything special about diamonds.

    We thankfully don’t have the diamond engagement ring tradition where I come from. Here we just use what you guys call a wedding band. When you actually get married, it gets engraved with the other persons name. I.e. you are supposed to exchange rings, so you get the one with the other persons name at the wedding, but since people don’t normally have the same finger size you just get the engraving done before the wedding.

    I would personally find it a bit offensive if I wore a ring (diamond or not) and the guy wore nothing. What’s the deal here? She is wearing a symbol that she is taking, but he is only taken when they are married?

  7. I'm with Rebecca on that– Some of the most beautiful stones are actually the "plain" ones the New Age Woo-Woo's try to sell for "healing" and "peace," anyway.

    Even gold is a bit boring– but I once saw a beautiful burnished (practically black) titanium wedding band. That was gorgeous.

    –And thanks, Rebecca; I have a lovely chunk of Afghani Lapis that I think I will take to the jeweler…have it made into a tie pin, or a lapel brooch, or summat.

  8. Yeah any decent jewelry store will have rings with empty settings that just about any gemstone will fit in. When I picked out my wife’s ring, I picked the ring first, it had some diamond in it I didn't want so they took the setting out and I picked out the diamond I wanted from a bunch of loose diamonds. Basically aside from the mall retail rings, most quality rings are completely separate from the gem setting. The setting is soldered into the ring, but can just as easily be removed and replaced with a similar gem and setting.

  9. On the issue of whether diamonds are worth it. I certainly agree that they are not worth the money, but it’s much easier to pay the price than convince your soon to be wife that diamonds are just a societal meme, only desired because of a huge marketing campaign. On a side note, the most interesting marriage rings I’ve seen, I had some friends that instead of having normal rings, got tongue rings for each other for their wedding rings.

  10. Rav: Cubic zirconia, usually manmade and extremely rare in nature, is different from zircon, a common, naturally-occuring accessory mineral found in many igneous rocks. The two are often confused, but the chemical formulas and properties of these materials are quite different!

    As for lapis lazuli, contrary to popular belief lapis is actually a rock made up of several minerals. Lapis is mostly lazurite but also contains calcite, sodalite, and pyrite. Lapis is a metamorphic rock that usually occurs when limestones are metamorphosed through contact with a hot, igneous intrusion.

    Why is Lapis blue? Lazurite and sodalite, major constituents, are blue. But that's not really an answer. In chemistry, molecules or elements that are responsible for color are called chromophores. Sometimes the major elements in a rock or mineral determine its color. Often, though, a very small amount of certain molecules or elements can determine/change the color of something. In minerals, trace element metals (transition metals, especially) are often responsible for determining color. Because trace element content is widely variable in minerals (unlike major element content), this explains why the same mineral can have a whole rainbow of colors. Shift the trace elements around a little, and the color of the mineral changes. Iron (Fe) and titanium (Ti) are elements that can be responsible for brilliant blue color.

    Honestly, I'd have to pour through my mineral books back at school to give a more detailed explanation of why lapis is blue, but I could figure it out… I'm sure it has to do with the major and/or trace metal chemistry of lazurite and sodalite.

  11. Can you find Peridot rings? Diamond may be overpriced, but it since it sells well many jewellers produce rings made of it. Peridot rings, on the other hand, could be quite rare, even in the gem itself is cheaper, so I’m not sure you would save any money.

  12. Are you telling me that my stainless steel Engineer's Ring would be somehow inadequate as an engagement/wedding ring design? Bloody Hell. I rather like the simplicity, myself.

    The trick being, I suppose, to find a woman who agrees with that particular (lack of?) aesthetic.

  13. Joshua, I support people doing whatever they want for their engagement rings or wedding rings. If you can find a girl who wants that sort of ring, good for you!

    Interestingly, my parents don't wear their wedding rings, which sit on a little dish on my mother's nightstand. They're very happily married, but they just don't like rings. They both work with their hands a great amount and find rings uncomfortable. I never even noticed until a friend of mine asked if my parents were divorced. She just assumed that because she never saw them wearing rings, they must not be married!

    Personally, I *love* sparkly, colorful minerals. I find diamonds boring, and I also have some moral problems with the diamond trade. So, I want a sparkly ring, just not a diamond sparkly ring.

    Then again, I'm worried about my career (not marriage!) currently, so I don't want any sort of sparkly engagement ring at the moment. Other sparkly sorts of jewelry are welcome, though…

  14. I vaguely recall Lucretius, the Isaac Asimov of Roman times, quipping about love: "A wedding ring grows thin with the passage of years, but we do not see flecks of gold departing from the ring, for gold is made of tiny atoms. . . ."

  15. Thanks for this. I have never liked diamonds that much. Once I realized they are just compressed carbon it just wasn't the same. I have a ring that was my grandmother's. While it contains a diamond, the value is seeing it on my grandmother's hand and her commitment to my grandfather.

    It really is to bad that society can't just accept man made diamonds. Just think about how this would change the politics of Africa. Also, you just wouldn't have movies like Blood Diamonds either.

  16. Darn. To think I spent all that money on diamonds. Sure it made her happy, but to think of all the beer/tools/Texas hold'em games I could have got for this is kind of sickening ;-)

    Evelyn, how about aquamarine?

    This is what I got my wife for our 20th.

    That's my first post here BTW. Great site ladies!

  17. Any fiancee that spend 2k (ore more!) on a ring should expect to have it handed right back.

    I don't want a stupid rock, mined in suspicious circumstances.

    If you're going to throw down cash, take me someplace fabulous or interesting for vacation!

    Who needs more things?

  18. I got a sapphire engagement ring instead of a diamond. It was much cheaper, & wasn't an "engagement ring", just a ring. The ladies at the stores were really, really horrified that I didn't want a diamond – you'd think I'd asked to have my ring set with dead puppies or something. It was incredible.

  19. You know, for 2k, you might as well travel to some place interesting and dig your own pretty rock out of the side of a mountain, then have that set into a ring. Makes for a much more interesting engagement ring and accompanying storu too. At least it shows commitment beyond just paying loads of money for the ring.

    I think I may just have to do that some day. And why not take the lady along so she can choose which rock is prettiest …

  20. exarch is ever the romantic, but yes, I like that idea much more than simply plonking down some cash for a diamond (although I'm sure that can be lovely too!)

    Like others here I've never seen the appeal of diamonds over other forms of rocks, except that there are some massive diamonds out in space the size of the sun (collapsed stars), and there's unlikely to be many earth-sized cubic zirconia's out in the depths of space.

    Wait a minute, that means diamonds are even *more* common. Hmmm…

  21. And lets not forget that many unscrupulous gem-dealers will "fill" their stones (i.e. patch up cracks and flaws). I can't recall if the documentary I saw was about diamonds or other gemstones, but if you go and buy a ring from that "less expensive foreigner" in the unsavory part of town, it's unlikely the stone even has a certificate, and you may eventually end up with a large crack running across your cheap rock, or worse, two halves of a – now worthless – gem.

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