Thank you for viewing. Size: Inner diameter approximately 16cm Stones: Approximately 7mm Purple mica silica is a power stone that makes you realize the importance of looking at completely different methods and ways of thinking when you've become stagnant on the way to your goals, or when things aren't going well and you're at a standstill. It seems to give you the courage to drastically change your current closed-off situation and jump into a new one.