Researchers at Environment Canada characterized diamondoid compounds for use in fingerprinting spilled oil distillates of low or medium molecular weight, e.g., diesel and jet oil. The diamondoids, a family of rigid, three-dimensionally fused cyclohexyl alkanes, feature cage structures that look like diamonds. The compounds are naturally occurring in oil. The ratio of different diamondoid compounds provides a regional signature for the oils origin. The flora and fauna in Saudi Arabia vary from those in Alberta, thus when organic matter decomposes with heat and pressure, diamondoids are produced in various amounts, providing a regional signature. Higher molecular weight diamondoids are not easily removed by evaporative weathering or altered by microbial degradation, thus diamondoids remain a usable forensic standard over a long period of time.