How to Create Custom Gems for Your Next Cosplay

Gems are used everywhere in anime, cartoons, comics, and TV shows. If you cosplay a lot, you’ll have to figure out how to make them at some point. It’s inevitable. If you’re lucky, you’ll be able to find ready-made gems that match exactly what you’re looking for. However, if your character’s gem is unique, you’ll need to figure out how to make them yourself.

The best way to create custom gemstones is by using resin to cast the gems. This will give you the most realistic result. If your gems don’t have to be clear, you can also mold them in clay and paint them with jewel paints or nail polish, or even use hot glue to create the gemstones.

I’ll go over these main three methods in this post. However, if you really want clear gemstones, I highly recommend going with resin. It may seem a little intimidating at first, but resin is not actually that difficult to use.

Method 1: Using resin to create gems

By far, the best way to create gems for cosplay is to use resin. This is the easiest way to create clear or transparent gems. If you’ve never used resin before, you may be a little intimidated by it, but it’s not that difficult to get started with.

You use resin with silicone or plastic molds. It starts as a liquid and you pour it into the mold. Over the next 1 to 2 days, the resin will harden into your gemstone. You can easily find molds for gemstones in various shapes and sizes online.

To use resin for gemstones all you need is:

• Clear epoxy resin and hardener kit
• A gemstone mold (silicone is best)
• Beakers and stirring sticks
• Gloves 
• Optional: Translucent dye or acrylic paint

1. Add equal amounts of resin and hardener to a beaker. Most types of resin can cause some skin irritation if they touch your skin, so it’s best to wear gloves for this whole process. Once the resin has cured (hardened) it is completely safe to touch.
2. Stir slowly for 5 minutes or until you no longer see streaks in the mixture. Be patient while you stir. If you try to go too fast, you’ll create bubbles that are difficult to get rid of. Be sure to scrape the sides and bottom of the beaker so that both liquids become completely incorporated.
3. Add a small amount of dye or paint if you’re coloring your gems (about ¼ – ½ a teaspoon). Stir until the color is thoroughly mixed in. Again, be careful not to stir too quickly so that you don’t end up with a lot of bubbles.
4. Pour your mixture into your mold. Fill the mold all the way up to the edge. If you notice any bubbles, use a toothpick to lift them up and pop them.
5. Let your resin creation sit for 24-48 hours. Once the resin cures, you can remove it from the mold and use it for your cosplay. You can drill holes in the resin if you want to use it as a bead or you can use hot glue to attach it to cosplay costumes and props.

Most types of resin will have a working time of 30-60 minutes before it starts to harden. Check the instructions that come with your kit for the working time of your particular brand of resin. This means you have to finish mixing the resin and pouring it into your mold within this time frame. To avoid bubbles in your resin creation it’s best to stir and pour slowly. 

You also want to work in a warm environment (about 75º-80ºF) and let the resin sit and cure in a warm place as well. If the temperature is a little cool, you can add the bottles of resin and hardener to a lukewarm bath for 30 minutes before starting your project.

• Resin 101: how to use resin and create custom silicone molds

What kind of dye to use for colored gems

If you want to make transparent gemstones, then you need to make sure you get the translucent dye. You can get dye specifically made to work with resin, but most acrylic dyes will also get the job done. If you are okay with an opaque color (for example, opals or pearls) then you can use acrylic paint too.

You can also add colors to create a swirling effect. Instead of completely mixing the color into the resin, you can give the mixture just a few stirs before adding it to the mold.

Method 2: Using jewel paints for cosplay gems

If you don’t want to use resin, you can also create a gem effect using some specific types of paint. These jewel paints are made to create a shiny surface that mimics the effect of a shiny gemstone. You can either paint the surface of any object or get clear costume jewelry and paint the backing.

You would need to use an object as your base and paint it with jewel paint. This could be something you created out of clay or any random object that is shaped correctly for your cosplay projects. It could even be a plastic easter egg if that’s what you have available. 

Make sure to use a fine brush when you are painting your gemstones. This way the surface won’t have scattered brush strokes that ruin the effect of the shiny paint. You will also want to sand your object until you get a smooth surface to work with. A rough or bumpy surface won’t look very much like a gemstone.

If you don’t have jewel paints available, you can often use nail polish to create the same effect. If you like how the nail polish looks on your fingers, it will probably have a similar effect on other objects. 

Method 3: Polymer clay with a varnish

If you like working with clay, you can create some pretty cool-looking gems with polymer clay. Clay gives you the ability to work without a mold and create any shape you want. While you can use just about any kind of clay you want, polymer tends to have the smoothest finish. This makes it better for the gemstone appearance that we’re looking for. Of course, clay can only be used to create an opaque stone, but there are many gemstones that fall into this category. 

Polymer clay is oven-dry clay. This means it will remain moldable until you bake it in the oven. At which point, it will harden and you will not be able to soften it again. 

Supplies you will need:

• Polymer clay (in white or various colors)
• Varnish

1. Mold your clay gem. You may want to swirl multiple colors together to create unique gems, or you can make solid colors.
2. Bake the polymer clay. Read the temperature guidelines on the packaging of your brand of clay to know how long the clay needs to bake and at what temperature.
3. Paint the clay. Use a soft brush to add any jewel paint or other paints that you want to ensure the brush strokes don’t show.
4. Add a varnish. Use a polymer clay varnish to create that shiny finish to the clay surface.

• Learn more about how to use polymer clay to make jewelry

Method 4: The hot glue gun method for creating gems

To make hot glue gems you need to get a special kind of glue stick that is transparent. You can use regular glue sticks, but they will create cloudy gems instead of clear gems. If you get clear glue and it’s still hardening to a cloudy color, that usually means it’s not cooling quickly enough. Try blowing on the glue or working in a cooler workspace to see if that works better.

You cannot mix color into hot glue, so you can only create clear gems. You will have to either color the gem with jewel paint or make the gem with a reflective, colored backing. Fortunately, this is easy to do with a little bit of aluminum foil.

Supplies you will need:

• Hot gluegun
• Transparent glue sticks
• Aluminum foil

1. Lay out a piece of aluminum foil and color it with a sharpie.
2. Put a large dot of glue on top and wait for it to cool and harden.
3. Cut the aluminum foil around the glue gem.

If you want your hot glue creation to be a specific shape, it can also be used with silicone molds, the same way resin is used. It’s a cheaper and quicker way to get similar results. However, you cannot mix color into the glue. You will have to either paint the surface or place a colored piece of foil as the backing.