As a collector who had purchased a number of different gemstones, I am a total geek when it comes to examining diamonds. In fact, I’ll be the first to admit my fetish for inspecting both rough and polished diamonds under the scope whenever an opportunity presents itself.

Recently, I purchased a batch of rough diamonds for my private study. To my pleasant surprise, I discovered that one of them displayed interesting triangular patterns on its surface and I stumbled upon “pyramids” on a diamond!

diamond trigons

Cool looking triangular features.

With the discovery of a feature I had never seen before, it got me elated and very curious. What are these patterns doing there and why do they form? After browsing several resources, I found my answers from a reference book by John I Koivula – “The Mirco World of Diamonds”.

This fascinating triangular shaped feature is called a trigon.

More Pictures on Diamond Trigons…

view of diamond octahedral

The other side of the same rough.

triangle patternings on diamond surfaces

The growth pattern can sometimes look like a series of triangles within triangles.

What Are They Really?

As it turns out, trigons are surface features that occur during the diamond’s growth process deep within the Earth’s mantle. They can appear on any shapes of rough diamonds and are a good indicator that the gemstone/rough is a diamond. Most other gemstones or minerals will not exhibit such growth patterns.

For more detailed information, check out this journal paper to see more photographs about trigons and how they form on different crystals.

Where Would You Find Them on a Polished Diamond?

While they can be a fairly common occurrence on the surfaces of rough diamonds, finding them on your diamond ring is really rare. Since the surface of a rough diamond is polished off to create facets during the cutting process, the trigons get wiped off the face of the diamond.

However, there are a couple of places in which they might still exist on a polished diamond. Take a guess. Where do you think you would be able to see trigons? If you made a logical guess that they will remain on places where the rough diamond is left untouched, you are right.

It is possible that trigons can be found on naturals or indented naturals of a polished diamond. Since the natural/indented natural is left as part of the original rough during the cutting process, that’s where you’ll be able to find them if they exist.

indented naturals on the diamond's girdle

Does your stone have naturals or indented naturals?

If your diamond has indented naturals or naturals, check them for the presence of trigons. But don’t fret if your diamond has them or if it doesn’t show any. It won’t change or affect the current clarity grade or the appearance of your diamond as they are already factored in during the grading process. They do however; serve as an alternate feature to help you identify your stone.

If you do find them, that’s a real bonus! I am sure these little creations of Mother Nature will fascinate you as much as they wowed me. Do take some photographs and share them with me. I would definitely love to see how the trigons on your diamond look like. offers you the tools to inspect diamonds up-close and enables you to see exactly what you will get when buying a diamond. They make it easy, fun and intuitive to shop for a diamond online. Check them out!

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  1. Nguyen Van An-
    April 6, 2015 at 12:31 am


    I have some diamond roughs with large trigons on the surface. I would like to sell them or put them up for tender. But I need the service or through your website.

    If you are interested, please contact me. I will send you my photos of the stone.

    Nguyen Van An

  2. Paul Gian-
    April 7, 2015 at 12:25 pm

    Sorry, we don’t sell diamonds on You might want to try eBay. Good luck!

  3. Deborah Wilde-
    October 24, 2015 at 11:17 pm

    Is the triangular feature only found on diamonds? I visited a diamond mind that also has 40 other types of gemstones and we just returned home yesterday I started looking thought my sifted centers that the mine allows visitors to take home, I found a crystal that I know I need to take to a jeweler or gemologist that has not only facets but a triangle pattern on it that caught my eye under the scope.

  4. Paul Gian-
    October 25, 2015 at 3:01 pm

    Trigons can occur on the surface a number of minerals. To confirm the diagnostic, use a diamond tester on the rough. That will give you a pretty accurate confirmation if it passes the test and has trigons on it.

  5. Moe josef-
    January 26, 2016 at 2:18 pm

    Hello dear. I would like to ask almost as the above question.! I found in Africa 2 colored diamond. I think one might be medium yellow diamond. And both have the pyramid trigons on them. And I took it to a jewelry store and we tested it with diamond tester and the number when straight to 10 on the device. So my question would lead like if you said the thing with pyramid trigons and a diamond tester passes how sure could it be that it’s an real diamond? Because here in Africa people rip of people and says that is not a diamond!!

  6. Paul Gian-
    January 26, 2016 at 2:30 pm

    If a rough stone has such features, it is likely to be a real diamond. That said, that doesn’t determine the diamond’s value as the majority of mined diamonds are so low grade that they can only be used for industrial purposes.

  7. Moe josef-
    January 26, 2016 at 4:02 pm

    OK I see. My ones are yellowish and white. Almost clear. One at 35 carat and one at 20 carat. I will attach a pictures to your email so u could see and get a better perspective. And by the way how is it to carry rough diamond. Example I got mine from my grandfather 5 years ago and I had them locked away with rubbish in the attic in my country in africa. I live in Sweden and born and raised there but I come often to visit relatives. Can I carry back with me these diamonds or is it rules and certified licence etc needed?

  8. Paul Gian-
    January 27, 2016 at 1:58 am

    Check with the local authorities. As far as I know, if you intend to import rough stones for businesses and trade, you need to do some paperwork. Since you are doing this on a personal aspect, these rules may not apply to you.

  9. Kenny McKey-
    January 22, 2017 at 3:10 am

    Howdy folks!

    Hey, thermal conductivity testing devices are not accurate for rough diamond testing. Rough diamonds often have foreign coatings on them stemming from the alluvial process. I have a letter from Ceres, who patented the thermal conductivity device, stating they do not support test results from their TC tester on rough minerals. The GIA says the same. Stick with identifying physical properties like hardness, habit, Trigons, cleavage, hydrophobic (scared to get wet), maybe fluorescence. If you found your mineral in a creek or river, is there a primary source (volcanic pipe), up river from where you discovered it? Press on and do not give up. Kenny McKey

  10. jerry winkle-
    June 5, 2017 at 9:00 am

    concerning trigons: what are the striation patterns shaped like a grid of diamonds inside of translucent type roughs called and why are they inside the rough

  11. Diane-
    April 27, 2021 at 12:58 am

    trigons can be found on quartz crystals, as I am sure you know by now . . . I have several on crystals in my possession

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