Worry stones are smooth, polished gemstones, usually in the shape of an oval with a thumb-sized indentation, used for relaxation or anxiety relief. The smoothness of the stone is most often created naturally by running water. The size of a worry stone is about half the size of a silver dollar coin in the United States. They are used by holding the stone between the index finger and thumb and gently moving one's thumb back and forth across the stone. This action of moving one's thumb back and forth across the stone can reduce stress.
Other names that worry stones may be called are: palm stones, thumb stones, fidget stones, soothing stones, or sensory stones.
As a folk practice implement, worry stones have many origins. Variations on the concept originate in ancient Greece, Tibet, Ireland, and multiple Native American tribes. The concept of a worry stone began by the simple action of picking a smooth stone and fiddling with the stone. Worry stones made by sea water were generally used by Ancient Greeks. Native American tribes would continuously give them to younger generations, creating a sense of connection from previous family members. They also believed these worry stones were considered a sacred item and they were extra special if they were made out of quartz.
From the perspective of cognitive behavior therapy, the use of worry stones is one of many folk practices that can function as psychologically healthy self-soothing exercises. Such techniques are imparted at an early stage of treatment, displacing any familiar but destructive coping methods (nail-biting, scratching, lip-biting, etc.) that the patient may have developed. This helps ready the patient to safely confront anxiety or trauma. Worry stones are simple and intuitive enough to be useful in therapeutic contexts where complexity and unfamiliarity are paramount concerns, such as when offering short-term treatment to refugees or children with post-traumatic stress disorder. After a patient has mastered a more sophisticated relaxation script for anxiety management, the worry stone itself can serve as a physical 'relaxation script reminder'; the patient may notice an impulse to use the object, and thereby become aware of their own anxiety.  The rubbing of the stone can create a sense of relaxation making the mind most relaxed and generating a sense of calmness.  There are also people that may use them during meditation practices, this is known to center a persons concentration benefiting the meditation.