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Anyone can grow a plant. Although actually I still believe that keeping plants alive is one of the most underrated challenges of adulthood. Growing a moustache is one level up. But have you ever tried growing your own crystal necklace? It’s not as hard as you might think.

When I grew my own crystal egg geode, I knew it wouldn’t be my last time growing crystals with alum. The process was just so fascinating! I already experimented with growing crystals in a piece of metal (a lid) back then. What if I would do the same for a smaller pendant shape? Would I be able to grow my own crystal necklace? I experimented a bit, and found that it is indeed possible. Of course I can’t not share these little gems with you.

1. Gather materials

You will need:
alum powder (Potassium Aluminum Sulfate)
nail polish
open pendant
necklace cord
necklace clasp

Where do I find alum powder?
You will probably be able to buy alum at your local drug store. It’s used to stop shaving wounds from bleeding. I was able to get a small block of alum, but had to smash and grind it myself into a powder.

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Get a pendant. It should be empty and preferably have a small edge on the side so you can grow your crystals inside. I got two so I could experiment with different colours and processes.

2. Paint the inside of the pendant with nail polish

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When I grew my crystal egg geode, I added food colouring to the water. However, I knew that the crystals themselves didn’t adsorb the colour. It was merely the eggshell and the edges that collected colour. So I figured that for my necklace I wouldn’t add any colour to the water. I would just paint the inside of the pendant with nail polish. I smudged the colours a bit to get a gradient in stead of coloured lines. I coloured one pendant in rainbow colours, the other one a blue ombre shade. Be sure to let your nail polish dry properly afterwards.

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3. Use transparent nail polish to ‘glue’ some alum powder to the pendant

When your coloured layer of nail polish is dried properly, add a layer of transparent nail polish. Then scatter some alum powder over the wet transparent polish. Push it in a bit and make sure it covers all parts of the inner side of your pendant.

What not to do: Don’t use white glue. This is what I used in my first attempt. Because I used white craft glue for my last crystal project, I figured it would work the same for this project. I’m not sure if it was because of a different underlaying surface or something else, but it didn’t work at all. After two days the glue had dissolved, the crystals hadn’t grown and it was a big fail.

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4. Dissolve alum in hot water

Boil water. Add about two or three big spoons of alum to a cup. Add a little bit of water and try to stir and dissolve as much alum as possible. Add another bit of water and stir. Continue this process until all crystals on the bottom of your cup are dissolved. You don’t want leftover crystals because then those will grow into bigger crystals, in stead of growing effectively in your pendant.

What not to do: Don’t use a microwave to dissolve the last bits of crystals. Some tutorials out there recommend this when you grow crystals. I did this last time as well. The logic is simple: you heat the water up so it will be able to dissolve more of your salt. There is a catch though that I didn’t think about: after a few seconds in the microwave, I saw a blue light flash. I immediately stopped my microwave. Something started to daunt upon me. Remember how salt water conducts electricity? Clearly a master of science diploma doesn’t say anything these days and will still make you blow up your microwave. Despite of this little incident my microwave still works as good as it did before (which wasn’t that good to begin with actually). But I though I should put a warning so you don’t attempt the same at home.

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5. Put your pendant in the water

Carefully drop your pendant in the alum water with a spoon. Place it on the bottom of the cup, nail polished side up.

What not to do: Don’t drop your pendant in when the nail polish hasn’t hardened yet. I didn’t wait long enough during my first attempt and it cost me a day. Because of this the nail polish kept sticky in the hot water. The crystals on top of the pendant dissolved and after a day or so nothing had happened so I needed to repeat the nail polish process. The second time I made sure to wait long enough (half a day or so before dropping it in the water).

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6. Wait

Don’t touch your cups or crystals for at least a day. After this time you should see some first results. You can get it out then, or let it soak longer for the crystals to grow even further. If they haven’t grown at all after 2 days, it’s possible that you didn’t dissolve enough alum in the amount of water you chose.

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7. Get your crystal pendant out of the cup

When you are happy with the shape and size of your pendant, get it out of your cup. If some crystals have grown on parts you don’t like (too much to the side or on the back) you can try to very carefully take these crystals away with a pin or needle. Let the pendant dry properly after that.

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8. Make your crystal pendant into a necklace

Put your pendant on a chord and make it into a necklace. Personally I like a black chord for this type of necklace, but you can choose anything that suits your taste to finish your crystal necklace to your liking. Try to be a bit careful when you’re wearing it. In the end it’s just salt crystals, so accidently hitting into something might cause your crystals to break. When you’re somewhat careful you shouldn’t have to be too afraid though.

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Yup, that’s it. And you know what’s even more fun? When people ask you about your necklace, you get to respond nonchalantly ‘Oh, I grew it’. How awesome is that?

Are you gonna grow your own crystal necklace? I would love to see a picture if you do!

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  • Reply

    RaChil Luke

    November 10, 2014 at 20:10

    I did this except I put the nail polish on top of the crystals! I also couldn’t get the crystals to grow on the pendent sections so I instead just mod podged them to the bases!

    I love getting to tell people I grew them :) It’s pretty awesome

    • Reply


      November 10, 2014 at 20:27

      Yes! I saw yours, they turned out pretty awesome! Getting them to grow on the pendants was quite a process, it took me several days and attempts before I succeeded. Gluing them onto them is also a smart solution. Is it strong enough though? I guess with the nail polish it will be pretty sturdy :)

  • Reply


    November 13, 2014 at 01:53

    I really like this idea. Have you tried experimenting with food colouring or ink or watercolour paint while you diffuse the salt in water? I would figure that the colour then would inherently become part of the crystal. Then any ombre colouring behind would make it pop more?

    • Reply


      November 13, 2014 at 09:55

      I have experimented with that, as I explain in my post. The colour doesn’t become part of the crystal, but merely reflects the coloured light through the crystal. Check out the egg geode post I did; there I added colour, but if you break off a piece of crystal it’s still clear.

  • Reply

    Angela Huggard

    December 3, 2014 at 00:42

    Hi there, I was just wondering if you could tell me how much alum you put dissolved in the water in each cup? Also, all I could find was already ground alum (in the spice aisle, the pharmacy said that they didn’t like to carry the larger blocks of it as apparently it can be used to make stink bombs) so the crystals are as fine as table salt. Will this still work? Thanks ; )

    • Reply


      December 4, 2014 at 11:44

      Probably about two full tablespoons. And yes, I would assume it would still work. I actually would rather get the alum in powder, because it’s easier to dissolve, but they only sold blocks at the store.

  • Reply


    February 9, 2015 at 16:34

    Hermoso trabajo, cuando lo haga te mando foto, felicitaciones!!! Ana

  • Reply


    February 12, 2015 at 20:49

    Hi ! I like a lot your tutorial, Can I ask you an advice ? I Would like to grow Crystals on a Polystirene Sphere. Do you think it will works ? is it better if I use White glue or something else ? Thank You … Bye Bye !!!

    • Reply


      February 20, 2015 at 10:43

      I really don’t know. Probably not all glues will work, I think some glues react quite aggressively unto Polystyrene, burning through the surface. Also there is the problem of not being able to sink the material in water. Of course you can try, but I have no experience with this material in combination with crystals whatsoever. Sorry. I am curious to know how your experiment turned out if you go through with it though :)

  • Reply


    April 4, 2015 at 16:45

    The reason why your microwave flashed isn’t because of salt water, it’s because the pendants are metal!

    • Reply


      April 8, 2015 at 02:23

      Actually no, because I didn’t put the pendants in the microwave, just a cup, water and the alum. Only later I added the pendants.

  • Reply


    May 7, 2015 at 16:11

    i hope this works. Do you think i will have success

    • Reply


      May 12, 2015 at 04:05

      If you follow the instructions and are open to experiment a little yourself with it as well I don’t see why not. If it doesn’t work for whatever reason, adjust it until it does :)

    • Reply


      August 3, 2017 at 00:57

      It’s because alum is ALUMINUM Sulfate. So you did add a metal into the microwave.

  • Reply


    September 9, 2015 at 01:03

    Question, Where would I get a pendant thing?

    • Reply


      September 9, 2015 at 09:31

      I bought it in a store where they sell hundreds kinds of beads, a jewellery material & craft store.

      • Reply


        September 9, 2015 at 16:43

        Ah OK, I’ll take a look. Ty for letting me know \(^_^)/

        • Reply


          September 9, 2015 at 21:57

          Also, how would I get the pendant ring (the thing that keeps the pendant facing straight) on the necklace? By the way, could you please make a video.

          • magicaldaydream

            September 10, 2015 at 08:01

            It’s the same kind of ring in terms of design you use for a keyring, only a mini version. How do you get that on? Same as you would with a key. Simply use your nails and wiggle the part in between until you succeed. I’m not planning on making a video. Have you checked out my crystal geode post yet though? Maybe that can help you as well?

          • Melody

            September 10, 2015 at 15:25

            Oh, I’m new to all this xD.

  • Reply

    Jacinta Nightshade

    October 27, 2015 at 04:37

    Do you know if I can make these with sugar or table salt?


    • Reply


      October 27, 2015 at 09:48

      I haven’t done this myself. Apparently you can use salt or sugar, but it will make your crystals cube-shaped instead of hexagon-shaped and probably give a less impressive result. But if you can’t get your hands on alum, you could give it a go and see :)

  • Reply


    February 14, 2016 at 02:01

    I have been looking for MONTHS on doing something different or unique w/the Geode Eggs. I haven’t even tried it yet but have been thinking of ways to stop outside everyone else’s regular egg. THEN, I found you. It’s like you wrote the JUST FOR ME..LOL
    I LOVE doing simple crafts & art etc.. but I have to take it to a step outside the norm.
    Thank you for sharing my “Step Outside Norm” for art. I look forward to exploring your site more & recv’ing ur emails.

    • Reply


      February 15, 2016 at 15:20

      That’s perfect! And I know exactly what you mean. I’m always on the lookout the create unique & playful DIY that are a bit outside of the usual, so I’m very happy to hear that you like it :)

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    March 28, 2016 at 17:08

  • Reply


    March 28, 2016 at 22:53

    I tried this and instead of using a pendent I improvised and used a beer bottle I followed all the steps I do everything right but it still wouldn’t work I’m going to try and re-do it hopefully will work this time if you have any ideas on how I could fix this or why it didn’t work please point that out because I don’t have any open pendants and I don’t know where to get any so please get back to me on this

    • Reply


      March 29, 2016 at 12:53

      You said you did everything right, so let’s go through the list: 1. You used alum? 2. How much alum did you use? 3. Did you solve everything until it was gone? 4. Were the small pieces of alum directly exposed to the water (you shouldn’t put nail polish over them)? 5 Did you wait until the nail polish was completely hardened before putting it into water? 6 Did you add extra alum to the water after seeing it didn’t work? 6. Have you tried growing the crystals on any other material (like have you seen my crystal egg geode tutorial)?

  • Reply


    August 11, 2016 at 08:39

    These are so pretty and I am planning to make some alum crystals with my cousins little girl when she comes to visit and I’d love to give this a go. Where can you buy open pendants from?

    • Reply


      August 13, 2016 at 17:42

      I bought them at a local store that sells tons of different beads. So perhaps your place has something similar? If not, you could always try online :)

  • Reply


    September 3, 2016 at 20:49

    I tried this several times and the crystals grew on the cup no where else.

  • Reply


    October 9, 2016 at 20:56

    Hey, I really want to try this but can’t find a suitable pendant base, I live in uk, Any idea of how to get one similiar to the one you used (Preferably not the circle one but the oval one), I have looked on Ebay, Amazon, Heinz and just can’t find a plain backed one like those, where did you get yours or did you have them before hand, I mean I even checked alibaba haha

    • Reply


      October 10, 2016 at 08:19

      I bought mine at a local beads store in my town. Perhaps if you send them an email you could ask them where they got their supply from? It’s a Dutch shop and they don’t have a webshop, but I just searched for their website, It’s:

  • Reply


    April 17, 2017 at 18:19

    I know this is an old thread, but how durable are these crystals? They break of just by touching them or is decent force needed?

    • Reply


      April 19, 2017 at 11:31

      Just touching them won’t directly break them. But if you hit them against something probably they will break. So wearing them won’t be a big problem. But if you wear them every day for a long time it’ll probably show. Also they might become a little bit less ‘shiny’. When you pour some water over them and dry them off again this will help, but wouldn’t do this too often for obvious reasons of it becoming fragile in water.

  • Reply


    November 26, 2017 at 02:40

    Hello! :D, can i ask? Where did you bought your open pendant, necklace cord, necklace clasp? I would also like to make one for my love one’s. Thank you :D

    • Reply


      December 5, 2017 at 15:46

      Check out my answer to Michael (2 comments up); he asked the same question. :)

    • Reply


      December 30, 2017 at 00:19

      Hobby Lobby has a good selection

  • Reply


    January 28, 2018 at 17:20

    I wanted to make this crystal spherical. Like, without any base. I wanted a gem stone lochet to put around a necklace. Like a pendant. Is it possible? Pls tell me how.

    • Reply


      January 29, 2018 at 11:54

      I don’t think that’s possible with this technique. Alum is a type of salt, so it’s quite fragile and breaks off relatively easily and dissolves in water. So if you let it grow on a sturdy base, it’s somewhat protected by that base. If it’s missing, I imagine it wouldn’t survive long. But I’ve never tried to make it myself, so I wouldn’t be able to tell you with certainty. This is my best guess. Good luck finding a technique that works!

  • Reply


    November 30, 2018 at 14:27

    Do you recommend sealing the necklace when it is finished with modge podge or something similar? Would this help make the crystals a little stronger to accidentally hitting it? Love the crystal ideas!!!

    • Reply


      December 3, 2018 at 13:16

      I didn’t do that, but that is probably a good idea. The crystals become less shiny over time and I think something like transparent nail polish would probably help to overcome that.

  • Reply


    May 17, 2024 at 15:46

    These are absolutely awesome! Such a fantastic guide, love it!


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