Crystals are often claimed to have healing powers, but there is no evidence that they are effective in treating any medical condition as of 2015. Crystals and gemstones, while aesthetically pleasing, do not possess special properties that allow them to interact with the human body.
Generally, positive effects of wearing crystals can be attributed to the placebo effect. A crystal is simply an ordered arrangement of molecules, atoms or ions into a symmetric repeating structure. For example, sugar (sucrose) can be found as either a crystalline or amorphous solid. Certain types of metals, such as copper, and magnets are also claimed to have health benefits much like crystals. Metallic and magnetic bracelets may be sold in health food stores or holistic healing centers, but scientific data supporting claims of healing are lacking.