Just a small bottle of essential oil requires a huge amount of raw material. So where corners can be cut to make these raw materials go further, and improve profit margins, well, lots of companies will do this.
Here’s a simple test to see whether there’s anything else lurking in the bottle other than essential oil.
If it passes this test, then you know there is a good chance the liquid is indeed pure essential oil.
Beyond this test, if you’re a full-fledged oil-geek, you’ll want to do further testing to assess quality as there can be a huge discrepancy from one ‘pure essential oil’ to another. A freshly cooked meal is not the same as a processed meal from last week that’s been reheated several times, even though they are both ‘food’, ‘a meal’ and ‘100% natural’.