When trace elements change in concentration or composition during a tourmaline crystal’s growth, striking color zoning occurs. These gems are called parti-color tourmalines and they occur in an unending variety of color combinations. Pink, white and green is the most frequently encountered trio and is sometimes referred to as “watermelon”. Tourmalines are designated as the October birthstone and for the 8th wedding anniversary. Primary sources for parti-color tourmalines are Brazil, Africa and Afghanistan.