Lepidolite crystal thumb / worry stones.  The colouring of these stones is purple with areas of white or black.  The front sides have indentations which should be used to rub your thumb over to distract your mind and reduce worry and stress.  

This stone reduces stress and aids sleep.

See more thumb / worry stones here

Country of origin: Brazil

Size: 4.1 - 4.3  cm approx measured at the largest points
Weight: 18 - 23 grams approx