Because of its high value, rose essential oil is one of the most commonly adulterated essential oils. Two of the main adulterants for rose oil are rose geranium oil, palmarosa essential oil (Cymbopogon martini), and geraniol (which is also present in rose oil) extracted from palmarosa because these oils have a similar scent profile to rose oil. Rose oil has also been adulterated with ethyl alcohol, phenylethanol, rhodinol, diethyl phthalate, as well as Guaiac Wood oil (Bulnesia sarmientoi; Tisserand, R., & Young, R. (2014). Essential Oil Safety. New York, NY: Elsevier). Guaiac Wood oil is often used in the adulteration of rose oil from Bulgaria and has a pleasant tea-rose-like aroma. One way to detect the presence of this oil in rose essential oil is to examine the microscopic guaicol crystals, which separate from the oil upon cooling and have a different form than rose oil crystals. The addition of Guaiac Wood oil to rose essential oil also raises the congealing point and increases the oil’s specific gravity.
Rose oil is also sometimes adulterated using cheaper reconstructions of rose oil made using damascones, b-ionone, (-)-citronellol, rose steroptenes and other rose alcohols. Another way that rose oil is adulterated is using b-phenylethyl alcohol, rhodinol fractions and adding less expensive rose oil (such as Turkish, Russian or Chinese rose oil to a more expensive one such as Bulgarian (Burfield, T. (2003-2008) Adulteration of Essential Oils and the Consequences to Aromatherapy & Natural Perfumery Practice. www.cropwatch.org).
Another indication that rose oil may be adulterated is its price. Because true rose oil is carefully cultivated and thus extremely valuable and more expensive, a significantly inexpensive rose oil is most likely diluted with other substances. When adulterated with rose geranium oil, for example, rose oil’s price may be significantly lower since rose geranium essential oil costs about 1/20th the cost of true rose otto.