Why DoTerra oils? Not only does DoTerra produce Certified Therapeutic Grade essential oils, they are pure oils taken only from natural resources, free of fillers and undiluted. No need to worry about unwanted contamination by chemicals or pesticides. They are tested AND cross-tested through the scientific processes of mass spectrometry and gas chromatography to ensure the highest level of purity. DoTerra Oils are a worry-free addition to your health and wellness regime.