A method of determining the constituents and impurities in mixed-color cullet to facilitate use of mixed-color cullet in glass manufacture is provided. A glass batch formulation is adjusted based on the measured characteristics of supplied mixed-color cullet. More specifically, certain preferred aspects of the present invention include the steps of providing quantity of mixed-color cullet, collecting at least one sample of the mixed-color cullet, performing, either singularly or in combination, particle size analysis, particle color analysis, or organics analysis of the mixed-color cullet, optionally storing the analysis results, determining a glass batch formulation, providing the cullet specification and the batch formulation to a glass manufacturer, and adjusting glass batch formulation based on the cullet specification to ensure consistent glass quality.