This stone is an excellent stone for meditation. It can be used to clear clouded areas of all the Chakra and especially to assist in opening the Heart Chakra. It is also believed to help activate the kundalini, or 'serpent fire' energies. By placing this stone on the Crown Chakra, it initiates the movement of kundalini energy up the spine. Relaxes one's overall nature. Clears the chakras and is excellent for enhancing meditation. 
Pictured are examples, (stones sold individually) shapes and color may vary somewhat
 
Small 20mm
Medium 25mm
Large 30mm
 
Serpentine Healing Properties and other items