Saybolt color --- an empirical definition of the color of a clear petroleum liquid based on a scale of -16 (darkest) to +30 (lightest). The number is derived by finding the height of a column of the sample that, when viewed through the length of the column, visually matches the appropriate one of three glass standards and referring to "Table 1 Saybolt Colors Corresponding to Depths of Oil" of Test Method ASTM D156.