Amethyst with a polished edge.  
 
This is one of my favorites in the collection, the polished sides sparkle and refract the sun as it streams through our windows.
 
Amethyst is a powerful spiritual stone associated with tranquility, intuition, and higher consciousness. Known as a "stone of sobriety" and protection, it clears negative energy, reduces stress, and fosters deep emotional balance and spiritual wisdom. It is widely used to enhance meditation and connect with the Third Eye and Crown Chakras.