John, I don't know much about grilling—I know somewhat more about beef. My father was born in Lithuania and apprenticed to a butcher at about the seventh-grade. He spent probably 60 years in the beef butchering industry and sort-of apprenticed me at about age 16. Although my education and career was not in his industry I stayed close to it and still remember his teachings, like how to sharpen a knife, how meat is graded and how to purchase it.
Meat is graded while still hanging as “sides” or halves. The grade is determined by the fat “marbling” within the meat. Marbling is determined by slicing into the rib cage, somewhere near the end but I don’t recall exactly where, and evaluating the exposed ribeye.
He counseled to remember that the entire side was not examined for marbling so a prime ribeye does not necessarily mean that other cuts will truly be prime. For general grading purposes and discussions there are three subgrades of the prime and choice grades. Proper aging will have more effect on the meat quality than the grading difference between prime and choice. And his final summation (he tended to deal in absolutes), “Buy top choice.”
I’m retired now and I still do it.
