It depends on the quality

Basic requirements for successful aromatherapy are high quality essential oils, the appropriate dosage and individual coordinated mixtures plus the most effective way of application. The following things should be listed on the label of the essential oil:

-        -  Description: 100 % pure/natural essential oil

-        -  The part of the plant from which the oil has been expressed

-        -  The plant name (Latin name)

-        -  The lot number

-        -  The extraction process