Candle diffusers, or oil burners, use heat to warm up essential oils to release their aromas, although they work in a slightly different way to electric diffusers. After mixing a couple of drops of essential oil to a small bowl of water, you place it onto a ceramic stand above a lit candle which heats the mixture to release the scent. If you are not sure which essential oil to use, a starter set is usually a good entry point, and it can also make for a good birthday or seasonal gift, as it features a range of 5 fantastic essential oils, including lemon, lavender, and tea tree.