When I was looking for faux gemstones for costuming, the choices were very limited. The colors were also boring and didn't have any of the natural variations I was looking for. So I made them myself out of a few basic craft materials.

These faux gemstones are intended to look like cabochon stones in whatever setting you desire. They have a sort of medieval flair to them. As such, I have used them in fantasy costuming, like the wizard costumes my family wore to Harry Potter book releases or Halloween costumes. However, they are a flexible embellishment that can be adapted for home decor and jewelry.

I have instructions for other fantasy craft items and examples of items with these gems in them posted on my crafting blog Craftastic World.

I also have a flickr photo group with pictures of these in use, if you need to be inspired. You can join it if you'd like and post your own creations: Faux Gemstones Photo Group

Step 1: Gathering Materials

You will need:
Clear or colored flat glass marbles
Aluminum foil
Permanent markers in colors that you like (I prefer Sharpies)
Polymer clay
Clay tools for your polymer clay
A glass pan (for baking the finished piece)

Step 2: Making It Sparkle

A shiny backing behind the glass stones creates reflectivity within the faux gem, allowing it to sparkle. Aluminum foil works well to achieve this. You can use either the shiny side or the dull side of the foil to back the glass stone but the shiny side has a better sparkle effect.

Tear off a piece of foil that is more than large enough to cover the bottom of the stone. You can use smooth foil or crinkle it for an interesting effect. I prefer it crinkled because it allows for more variations in color. If you want a crinkled effect, wad it up several times first. Smooth out the foil or, to get really deep creases, press down on the foil to flatten it. This retains the deep creases and prevents the foil from getting holes when it is over-worked.

Step 3: Color

To add other color elements to colored glass stones or to create a unique color effect out of clear stones, use your permanent markers to color the shiny side of your piece of foil. You should also color the flat back side of the glass stone you are using.

Swirl together different colors and experiment with the results but be warned the different colors will bleed together onto the tip of the markers. (I just ran the bled color out by scribbling it on paper.)

For more variations, dab clean foil against the coloring while it is wet (to blend colors together) or blot it the colored portion with paper to remove heavy color. Another way to create a swirled or varied coloration is to add other colors and patterns in permanent marker on the flat back side of the glass stone. When the foil and stone are put together, youll combine both effects for a unique look. Continue to the next step once the marker is completely dry on both the foil and glass.

Step 4: Backing the Stone

Place the glass marble against the colored side of the aluminum. Cut a circle out of the colored foil that is larger in diameter than the base of the glass stone. I did this by holding the stone against it while cutting around it. Center the stone on the foil and press the overlapping edges up the sides. Press the folds flat against the stone.

Step 5: Making the Setting

I won't go into a long treatise here on how to use polymer clay. There are plenty of places online that can provide more comprehensive details on the subject. Polymer clay works very well for making brooches and medallions into which your new sparkling gem can be set.

Create the setting by pressing the stone into a base of unbaked polymer clay and building up the clay around the stone. If you already have an unbaked polymer clay piece that you want to place it on, use that. Otherwise, you can simply make a circular base that's large enough to accommodate the stone. Carefully press the stone and the attached foil onto the base, making sure that the clay conforms well to prevent air voids.

You need to surround the sides with clay in some manner. You can make a rope to encircle it or press down little balls of clay around the stone--anything you can think of. The foil and stone will not stay stuck to the base without something holding them on, like the setting in jewelry. The main goal is to embed the stone in clay well enough so it cannot fall out while you also want to cover the sides of the stone to hide the foil and coloring work.

Step 6: Finishing

Embellish the clay piece further, if desired. If you want it sewn on or used as a necklace medallion, make the appropriate holes in the clay prior to baking.

Place on a glass pan and bake your clay piece as instructed on the packaging of the clay. I just use my home oven but I know there are people who worry about clay and marker fumes. So, if you are worried, use an oven dedicated to polymer clay work and ventilate if possible.

Slap that sucker onto a brooch back or use however you'd like.