As seen in many trades, the more expensive and popular a commodity is, the more adulteration occurs. Unfortunately, jasmine falls solidly into this category and is commonly blended with other chemicals, natural and otherwise, in an effort to pass off the impure oil as pure and at high prices. In contrast to the high price of pure jasmine absolute, an ounce of synthetic jasmine oil costs a fraction of the price: typically around $4. Thus, natural/synthetic blends of jasmine are typically used in the perfume, body care, and flavoring industries.
When jasmine absolute is adulterated, it is typically by addition of indole, amyl cinnamic aldehyde, synthetic jasmonates, ylang-ylang fractions, and other forms of jasmine oil such as jasmine absolute by châssis. (Arctander, S. (1960) Perfume and Flavor Materials of Natural Origin. Artander) There are also a few absolutes/attars made from similar smelling plants and they sometimes are noted as jasmine.
However, a trained nose will be able to tell the difference between an adulterated jasmine and a pure oil. In addition, gas chromatogoraphy/ mass spectroscopy analysis will reveal any adulterations other than what a typical oil will contain.