You may have heard that sometimes the essential oils you purchase could be less than pure. Oils labeled as pure essential oils may be diluted with cheaper carrier oils, emulsifiers or solvent without you even knowing! This can make them less than ideal for topical use (even diluted as directed) or diffusing, so it’s important to know for sure that what you have is really a pure essential oil.

Luckily, there are a few easy tests that you can do at home if you are curious to confirm the purity of your oils.

Test #1: Study the Label

This is the very easiest test, as all you need is the essential oil bottle with label! Every essential oil label should ideally list the following:

1. Latin name: you need to know this because common names vary and certain essential oils actually share a common name. The Latin name is the plant’s true name and it is what it is — no ambiguity here.
2. Status: this means how the plant was grown. Was it conventionally farmed, meaning it was exposed to herbicides and/or pesticides? Is it certified or non-certified organic? Or was it wildcrafted? The answer may affect how, where and when you choose to use the oil.
3. Country of origin: chemical makeup of an essential oil will vary depending on where the plants were grown. If there is no country of origin listed, the oil in the bottle may be a mix of oils from the same plant but many different sources. A country of origin listing is an assurance that your essential oil is from a single source.
4. Method of extraction: there are a number of different extraction methods, and the method used should be made clear on the label. This might be solvent-extraction, steam distillation, cold pressing or CO2 extraction.

Checking to make sure your essential oil label includes all of this information is the first checkpoint in buying a quality oil.

Now, onto the tests that ensure nothing has been added to your essential oil.

Test #2: The Rub Test

Place a drop of the essential oil on the tip of your pointer finger and rub your finger and thumb together. If it feels oily, it likely has a vegetable oil added. Dilution can be a great way to make expensive oils more affordable and accessible, but they should be clearly labelled as such. Diluted essential oils should not be used in the diffuser and may void your diffuser’s warranty.

Test #3: The White Paper Test

For this test, you’ll need a scrap of white paper for each oil you’d like to test. Place a drop of the oil in question on the paper and let it dry. If the oil has been diluted, it will leave an oily residue that is slightly transparent. If it’s a pure essential oil, the spot should eventually dry to be almost invisible, leaving only its shadow. It may be helpful to place a drop of vegetable oil on one scrap and a drop of essential oil that you know to be pure on another to use as reference points.

Test #4: The Water Drop Test

An essential oil that is pure, as well as essential oils that have been diluted into carrier oils, will float on top of water. Meanwhile, because the purpose of an emulsifier is to help oils mix with water, an oil that has been cut with emulsifier or solvent will mix slightly with the water, creating a milky appearance. To perform this test, simply fill a clear glass with clean water to the halfway mark, add a couple drops of the oil in question and stir to test whether the oil emulsifies or mixes. If the water turns milky or slightly opaque, a solvent has been added to your oil.

Test #5: The Sniff Test

Most essential oils have a shelf life of about two years, with the exception of citrus oils which should be used within a year. Meanwhile, vegetable oils only have a shelf life of about six months to one year. This means that an essential oil that has been diluted in vegetable oil will go rancid much quicker than most pure essential oils. So if your oil smells off but you would have expected it to last much longer, chances are it was diluted in a carrier oil.

The takeaway? Buy your oils from distributors who offer as much point of origin information as you can get; and if you discover an essential oil is adulterated, consider not buying from that supplier in the future — you may be paying much more than you should be for a product that is of questionable origin and quality!