Maybe I'm off base here, but I thought the outer perimeter was chrome, with semi-black in the trough. I thought everything inside the black trough was textured argent as you see remaining left in the recesses (the rest is weathered away). Bolt heads are semi-black also. So in short, the only chrome finish is the rim around the edges and the 340-s text. On non-hp cars, the same perimeter chrome and black in the trough and bolts with chrome ribs/vents, the rest textured argent.