Because of its high fat content, bluefin is especially prized as a raw product and is marketed in three grades. No. 1 “sashimi-grade,” the freshest and fattiest, goes to the Japanese market. No. 2, next best, is “grill grade.” Nos. 3 and 4 reflect diminished quality. Bluefin is the darkest and fattiest of any tuna, and its uncooked meat is red. When cooked, the meat turns firm and an off-white or ivory color. The flavor is distinctive. The flesh has the firmness and appearance of beef steaks. Raw bluefin meat can be brined overnight to mellow the flavor.