If you've ever wondered why one bottle of lavender essential oil costs £2 while another costs £30, you're not alone. Most people assume that if an oil smells like lavender, it must be lavender. But as a doctor and aromatherapist, I've learned that scent alone tells us very little about what's actually in the bottle. In this article, I explore adulteration, authenticity, sourcing and testing - and why quality matters if you're using essential oils for more than just their arom