In the United States, there is no rating system for essential oils. The closest we get is an FDA requirement that in order to label a bottle of essential oil “pure” or “therapeutic grade,” the contents of that bottle must contain at least 5 percent essential oil! Guys….only 5 percent! That is crazy town!.All oils in the world fall into one of 4 categories: Grade A is therapeutic, made from organically grown plants and distilled at low temperatures..Grade B oils are food grade, but may contain synthetics, pesticides, fertilizers, chemical extenders, or carrier oils..Grade C oils are perfume oils that often contain adulterating chemicals. They use solvents, for example, hexane, to gain a higher yield of oil per harvest. Solvents can be cancerous, and are in many store bought oils. They may also be diluted 80-95 percent with alcohol..Grade D is called “floral water,” which is aromatic only and is usually a byproduct of Grade A distillation. After all the oil is pulled out, the leftover trash water is sold to companies which will fill 5 percent of the bottle with this “leftover trash water,” fill the rest with carriers, and then label it “pure”. .Grade A is the only pure oil. Grade D would be like walking into your fridge, taking a glass of orange juice and diluting it 95 percent before you drank it! It would not have the full benefits of orange juice. That’s why you want Grade A oils. Before you purchase, check to see if the company grows their own plants, owns their own fields, and controls the entire process from the farm to the sealed bottle. Pesticides, pollution, previously farmed land - all of it can affect the quality of an oil. Most essential oils are sold more cheaply because companies cut corners. Young Living oils are Grade A.