Iodine solutions can be brown, blue or purple in color, depending on the characteristics of additional elements. According to About.com, pure iodine is blue and black but makes a purple solution when mixed with chloroform, carbon disulfide and tetrachloride. Iodine turns blue when it comes into contact with starchy elements.
Iodine is used as a disinfectant and in the treatment of thyroid disorders. Most disinfecting tinctures vary from dark to light brown in color, according to the strength of the solution. Lugol's strong iodine, a popular supplement and topical disinfectant, is mixed with 5 percent of iodine and is a dark brown, translucent liquid.