The Gemstones listed below are my preferred choice, chakra goes by colour so any appropriately coloured gemstone will work.
White/Violet (Crown)Thought. The overall balance of the Chakra System
Indigo (Third Eye/Base) Light.
Understanding, knowledge and
Blue (Throat) Sound.
Communication, personal expression and flow of information.
Green (Heart) Air.
Relationships and personal development.
Yellow (Solar Plexus) Fire
Self confidence and personal power.
Orange (Sacral) Water
Creativity, emotions and sexual drive.
Red (Base) Earth
Stability, energy distribution and physical survival.
Black - Grounding