That's what our YH-100 drivers look like.
..Or is it dead gray with visible milling marks, as in this photo:
This is what our HP-1 and YH-1 drivers look like.
EDIT/UPDATE: It turns out that the HP-1 had a stepbrother, which we've called the HP-1 Anisotropic. It was spec'd just like the HP-1, and Yamaha still called it an HP-1, but the magnets had the "keeper" plates on them shown above, giving the Anisotropic model about 2dB more efficiency. The box is different too: the HP-1 box is silver with black writing; the HP-1 Anisotropic's box is black with white writing. But everything else is the same, so the only way to be sure you have the Anisotropic model is to shine a bright flashlight into the cup to check the driver's surface. We know of two HF owners of this rare variant, Komi and JadeEast. However, this doesn't answer the question of whether Yamaha "voiced" the headphone differently for different markets.
.