QUESTIONGranite Quality - I'm trying to find out how to differentiate granite by grade/quality Thank you...
ANSWERANSWER - It is very difficult to differentiate granite let alone any other stone. People in the trade through experience may be able to notice key characteristics by looking, but even then it is very subjective depending on the person's experience. It is one thing to determine quality in terms of performance criteria and another to determine quality of stone in terms of color. There are not standards for color.
ANSWER - There are some national ASTM standards and tests for certain types of stone that quantify several performance minimums to be considered standard grade material of that type. It does not address degree or consistency of color. Granite's category has an ASTM C615 standard that specify minimums for density, absorption, modulus of rupture, flexural strength, water absorption, compressive strength, and abrasive resistance. It costs about $1200 to perform these tests, plus shipping costs, which I can provide those services.
Best thing to do is work with an importer/distributor/fabricator that has been in business for awhile and has good references. Good luck!