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
Clear or colored flat glass marbles
Permanent markers in colors that you like (I prefer Sharpies)
Clay tools for your polymer clay
A glass pan (for baking the finished piece)
Step 2: Making It Sparkle
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
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
Step 5: Making the Setting
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
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.