Maple syrup is divided, for commercial purposes, into five different grades of color. Color is one of the chief factors in grading maple syrup. The lighter the syrup, usually the more delicately flavored.
"Government grading stipulates that the maple sap, free from foreign material, and of a density of 66 degrees Brix hydrometer reading (66% sugar). It should possess a characteristic maple flavor, should be clean, free from fermentation, and free from damage caused by scorching, buddiness, any objectionable flavor or odor, or any other means."
If you want to know more about maple syrup grading please refer to the following site: http://www.siropderable.ca/home.aspx