There are many synthetic oils out there and they are basically garbage. Some good companies are Plant Therapy (Robert Tisserand), Pacific Institute of Aromatherapy (Dr. Schnaubelt), and Tropical Traditions, which carries Florihana, which is made in France. Also, Now oils are very good and reasonably priced...especially for topical applications or diffusing. I use Young Living for oils I take internally, but otherwise I use other oil companies for diffusing or topical use, since YL is so expensive.