Compare the smell of different brands of oils. Don't put your nose right up to the open tester and sniff - the undiluted oil is strong and can give you a headache. Instead, hold the lid at least 5 inches away from the nose and sniff.
When comparing a variety of scents, take breaks. Sniffing too many different oils close together can overwhelm the senses and temporarily reduce your ability to discern differences in different essential oils.
Avoid buying essential oils from a company that prices all different oils at the same price. It may be a sign that the oils are synthetic. The price of natural essential oils should vary greatly according to how much of the raw material is needed to produce the oil.
Avoid essential oils that have been diluted with vegetable oils. To test, place a couple of drops of the essential oil on a piece of paper. If the oil leaves behind an oily stain, it has likely been diluted with vegetable oil.
Choose companies that list the latin name of the essential oil on the bottle as well as the common name, so there is no confusion. In addition, the company catalogue should indicate the country of origin and method of extraction for each oil.
Choose pure essential oils over synthetic essential oils. Aromatherapists prefer pure oils, saying that synthetic oils do not have the same therapeutic properties as pure essential oils. Also, synthetic oils are thought to cause more headaches and allergic reactions.
Look for "pure essential oil" or "100% essential oil" on the label. Avoid "fragrant oil", "perfume oil" or "aromatherapy oil", which can be warning signs that the oils have been mixed with chemicals or other substances.
Although the words "pure essential oil" is a good sign, it doesn't say anything about how the plant was grown or how well the essential oil was stored.
Essential oils should be sold in dark amber or blue glass bottles. Clear glass can allow light to cause the oil to spoil.
Don't buy essential oils in plastic bottles, as the essential oil can dissolve plastic and contaminate the essential oil.