Dis Hamilton grade 992 always have a gold center wheel or did these start appearing at a certain date and serial number?

I think they started on the model 2's William, and to my knowledge I don't think they were solid gold, just gold plated the same as the 950B & 992B movements.I could be wrong though and have been before.Someone else will chime in with more info hopefully or with a drawing/blueprint of the wheel maybe.

Post update:

I have come across an article from the early 80's William where it was mentioned that Henry Fried stated the 992 wheels were 14Kt solid gold, this is the only reference that I have found to this effect, Although I have seen others dispute it then, and through to this day.

If they were solid gold I am amazed that they were not advertised as such by Hamilton as it would have been a marketing edge in my opinion, but I am yet to see any such advertisement with this in.

The 992B and 950B were definitely gold plated, as for the 950 Grade, if H Fried is correct about the Grade 992 then I would be under the assumption that the 950 would be solid gold as well. Maybe Lindell or someone else with more knowledge about these could enlighten us more?

Or one day maybe someone will destroy a couple to see their make-up and settle the debate once and for all

I found a broken 992 gear and it looks like plated brass under a loop.
Hard to photograph and hard to tell from the pictures.
Under side view on the left.
Problem is, just because this one looks to be plated, doesn't mean some were not solid.

Steve