DIY Sparkly Geode Crystals w/ Polymer Clay


I love collecting minerals, especially geodes.  There is something so magical about minerals and gemstones.  To me, they are like a piece of heaven that fell from the sky.

But as much as I love collecting geodes, they can get pretty expensive so I  I thought it would be great if we could DIY our own! I was inspired by Geode Eggs that I saw from Martha Stewart. Instead of using fragile and tiny egg shells, I wanted to make our own base for these sparkly geodes with polymer clay as a base!

It’s a pretty easy DIY that only involves a few ingredients and a few steps, and the result is so pretty! small-DIY-GEODES-2

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Alum Powder

Polymer clay

-Glue and foam brush

-Measuring cup

Food coloring



1. Take out one block of polymer clay and knead it until it softens. If you want to get a marble look, you can mix two colors of clay together. Once the clay is nice and malleable, use your thumb and palm to press the ball of clay down until you get a flat disk. With your thumb and forefinger, pinch around the edges until you create a bowl-like shape.


2. After forming your bowl, bake the clay by following the instructions on the packet. Make sure to let the clay fully cool down before moving onto the next step.


3. Completely cover the inside of the bowl in glue. You can do this by pouring in a generous amount of glue into the bowl and using the foam brush to spread it around evenly.


4. While the glue is still wet, coat the inside in alum powder.


5. Mix together 1/2 cup of alum powder and one cup of hot water, making sure that the powder completely dissolves in the water.  Then add in about 10-20 drops of food coloring.


6. Once the glue and the alum powder has set, put the bowl into the mixture. Let it sit overnight, then check in the morning how your geodes have crystalized!


Carefully take them out of the solution and let them airdrop for at least 24 hrs.  You can reuse solution by heating it up in the microwave and restating to dissolve the alum.  Add more alum as needed to the solution.

Watch the video here:


16 comments on “DIY Sparkly Geode Crystals w/ Polymer Clay”

  1. Hello! Absolutely love this diy. I tried making these and they did not turn out like yours. I even ordered everything on Amazon. The alum would not completely desolve even with hot water. I let it soak over night and the next day it was a salty mess. Did not crystallize at all. Can you use white elmers glue?

    1. Hi Christie! Hmm, for the Alum step, when you kept mixing it, it didn’t dissolve anymore? Also, overnight, did any crystals form(not just in the geode, but in your container as well?) If nothing crystalized, perhaps the Alum you received was not good. It needs to be the consistency of table salt. The larger flake version dosent work well. Let me know and I will try to keep helping you.

      1. I did this yesterday afternoon, and I woke up in the middle of the night and fished around in the solution, couldn’t find the clay bowl. It dissolved! Knowing that really wasn’t possible, I located it on a nearby table, I forgot to put it in! So, I reheated the alum solution to dissolve the crystals again, and dropped it in. This morning, after about 9 hours, it’s perfect. I intend to do this over and over in different colors. I used white Elmer’s, since I didn’t have the clear, and gel food coloring ‘cuase that’s what I had. Thanks for this tute!

  2. Hello.

    Can you tell me how long you allowed the glue and alum “to set” before submersing them into the liquid?

    Thanks for your help and the post.

  3. I used everything that was needed. BUT…step #5 didn’t work!

    5. Mix together 1/2 cup of alum powder and one cup of hot water, making sure that the powder completely dissolves in the water. Then add in about 10-20 drops of food coloring.

    The alum powder did not dissolve in hot water. I already poured my powder in the hot water and at that point was stuck.

    So I poured the solution into a glass jar and put the glass jar into a pan of water on the stove and boiled the water to dissolve the powder.

    Once dissolved I put in my geode. and let sit overnight. I was happy about the way the powder formed into crystals but they didn’t stick to the clay.

    I will try again this time letting the solution cool off before putting the geode in it. I think the hot water melted the glue and maybe why it didn’t stick.

    I had to add glue on top of the crystals to make them stay.

  4. LOVE THIS! Going to try it today. I also collect (or as my hubby says “hoard”) crystals and minerals. I also work with the polymer clay so both my faves in 1 is a good thing. Thank you for this 🙂

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