Step-by-step instructions: 1. Buy some sunglasses. Make sure they have polarizing lenses. 2. Get a computer monitor. 3. Holding the glasses in front of the s

Step-by-step instructions: 1. Buy some sunglasses. Make sure they have polarizing lenses. 2. Get a computer monitor. 3. Holding the glasses in front of the screen, rotate them until the angle is such that the screen appears black when looking through the lenses. 4. Make a note of the angle. In this configuration, the combination of the glasses and the screen serves as a homemade polarimeter. 5. Throw all that shit in the garbage. 6. Just look at the glassware edgewise, if it's greenish it's soda-lime.