That's interesting Eric, thanks. I confess I haven't looked particularly closely before.

I wonder if we can tie it in more closely with years - I don't have serials linked to my photo archive unfortunately. Certainly all the Dato 45s have notably silver dials, so by '66-67 that may be the norm, but the Dato doesn't necessarily signify for other models as it needed a separate run anyway for the date window.

Some of the more matte dials have T marked too, though the date that is introduced varies by jurisdiction so doesn't necessarily help us out a great deal.

The watch on the left here is the earlier, with a matte dial and T marking:

The second execution dials seem to have some natural variation too, so it's not as straightforward as matte > metallic > matte. Maybe it's matte > metallic > matte > mixed all over the shop!