Sphatik shivling is considered to be auspicious and praying and bowing down to sphatik shivling is considered to be bowing to Lord shiva directly.
Sphatik (rock crystal) is the purest and the most auspicious gem in the world.It believed that during "Ramayan Kaal": Lord Ram and Laxman sat on the sphatik rock. Any idol which is made of Sphatik does not need "Pran pratishtha" before worshipping. Worshipping a Sphatik shivling is considered to have same effect as worshipping the "Jyotirling".
Worshipping of Sphatik shivling brings peace, prosperity and happiness to the house where it is Worshipped