Heat oil in a small saucepan over medium heat. Add ginger and garlic and cook, stirring constantly, 1 minute. Add blueberries and honey and cook about 1 minute until juice is released. Pour in port and vinegar and arrange rosemary sprigs under the surface of the liquid. Bring to a boil, and cook until liquid is thickened and reduced, about 20 minutes. Stir occasionally. Sauce can stand at room temperature until meat is ready.

Preheat the broiler. Season both sides of lamb chops with salt and pepper. Broil 4 minutes on each side for medium rare, 5 minutes on each side for medium, and so on. Place lamb chops on a serving platter and let stand for 2 to 5 minutes re heat sauce over medium high heat for 1 minute, if necessary. Remove rosemary sprigs. Spoon over lamb chops or pass separately.