DōTERRA CPTG Essential Oils Wellness Advocate. When you choose doTERRA, you are choosing essential oils gently and carefully distilled from plants that have been patiently harvested at the perfect moment by experienced growers from around the world for ideal extract composition and efficacy. Each doTERRA essential oil is also carefully and thoroughly tested using the strict CPTG Certified Pure Tested Grade quality protocol. Experienced essential oil users will immediately recognize the superior quality standard for naturally safe and pure oils.