Instructions
Pick up the red stone that you want to identify and hold the stone as close to your eye as possible.
Turn and look at a light source, like a light-bulb or a window, so that the stone is between you and the light source.
Slowly roll the gemstone on its axis between your fingers, looking through it all the time. You should see rainbow refractions. If the rainbow is missing most of its yellow and green coloring, you have a ruby and not a quartz crystal or other type of red gemstone. Rubies have high concentration of corundum, a mineral that absorbs most of the yellow and green portions of the spectrum. A quartz crystal will show a full spectrum rainbow, due to its low mineral count.