Kind old topic, but I thought I'd put in my two cents! My mom is a massage therapist and essential oil enthusiast, so I've learned a lot about them from her, for the most part, and a little on my own.
Essential oils (high grade, usually marked as therapeutic grade essential oils) are gathered by steam distillation or cold-pressing. There are two "schools of thought" concerning essential oils, the French and the English (lol). While the English school says you should always dilute your oils, the French says that essential oils should always be used directly on the skin unless a negative reaction occurs. In that case, oil (NOT WATER) should be used on the afflicted area to reduce the irritation.
Because Beth uses steam distilled and cold-pressed oils, her materials are considered essential oils. Essential oils have an approximately infinite shelf life, but because BPAL oils are blends, the oil may not last as long. This isn't to say that the oils will "spoil", but the blend will be compromised after a certain amount of time.
So - Beth uses essential oils, but the product she produces is considered a perfume oil. Synthetics seem to be out of the question, but scents from plants where the oil can't be extracted through these means are created through a bouquet or blend (a combination of scents that approximate what it would really smell like). The site says that perfume oils are 85-100%, but consider what I said before about the difference between perfume oil/essential oil.
Hope that clears things up!