The best all around and arguably the most versatile crystal around is Clear Quartz.  The ability to amplify the power of nearby crystals brings much value to Clear Quartz.  Self-cleansing, this type of commonly found quartz also has the power to cleanse other nearby crystals.  Properties of Clear Quartz also include, purification, clarification of thoughts, divinity and harmonizing mind body and spirit.  Clear Quartz is great for a first stone and a great all around crystal to keep nearby.