At about $15 a gram, saffron is the world's most expensive spice. Rumi Spice has a unique model of employing Afghan farmers who are growing it that aims to double or even triple their annual income. Cristina Hirschkorn/Courtesy of Rumi Spice hide caption

itoggle caption Cristina Hirschkorn/Courtesy of Rumi Spice

Pepper is the spice most commonly contaminated with salmonella and other pathogens. iStockphoto.com hide caption

itoggle caption iStockphoto.com