The jeweler cradles it in his hand, scrutinizing it through his eyepiece. “Flawless,” he mutters, in a hushed, reverent voice. “A perfectly flawless crystalline structure.” He brings it to his face. He opens his mouth. He eats it. “Delicious!” Like a gem stone’s luster, a chocolate bar’s flavor depends largely on the crystalline structure of the chocolate’s chemicals. Learn more on this Moment of Science.