Gather several lead crystal glasses. Fill each with a different amount of water. This will help them create different tones. The more water in a glass, the lower the tone will be.
Dip the tip of your finger in water. Gently rub the rim of one glass with the tip of the wet finger until the glass begins to hum. You will feel the vibrations starting before you will actually hear the sound from the glass.
Change the pressure or amount of wetness on your finger to change the sound produced by the glass. You can also change the pitch by adding or removing water from the glass.
Re-wet your finger as necessary to remove oils from your finger and to keep the proper amount of friction between your fingertip and the edge of the glass. This will ensure you keep the same sound coming from the glass.