...is the variability in the Monaco text and the Heuer shield and text. The dialmaking process is actually in large part a printing one, which allows for a high degree of repeatability rather than wide natural variability that we see in these. I understand that these are arranged in blocks, so the block for the shield and model name can be used in several models rather than requiring a bespoke unit for each model. This gives consistency across models as well as within the model range. Because of this, you can sometimes start to see family traits.

Take a look at these 3 original Singer Monaco 73633 B dials:

If you look closely, you'll see that the right arm that forms the bottom "curve" of the "U" is marginally longer than the left arm on each of the watches. Looks like slightly different amounts of ink have been applied in each case, but that quirk remains so it is probably a function of the original printing block. The "R" is too close to the second "E" compared to the "H" and first "E" on these Monacos (and many other watches too, usually less markedly than here) but the important thing is, it is consistently too close, as a result of the printing process.

Singer did a great deal of the dial work for Heuer, so we see good consistency across model ranges too - the subtle serifs on "Heuer" will look much the same on a Carrera as on a Monaco for instance.

Now, let's look at some of the disputed dials, including some with white dials and waffle markers as well as the blue/blue ones.

First thing to note is we're not seeing the same sort of consistency with the Heuer and Monaco scripts as we do with the Singer dials. There are some similarities between them, but not the accurate repeatability of a professional printing process. It's quite possible that Heuer employed another dial manufacturer other than Singer as part of trying to sell these at a lower price, but the quality feels too far off - even by the late 70s, Heuer would have been in a strong enough position to reject them.

Now, that blue/blue one is better than a lot of them (closed 4s etc), but the text does completely lack serifs. That it does, and that the three below and Bucherers exist with painted markers:

is, in my opinion, cause for continued questions over Heuer-marked blue/blue dials. If Heuer wanted a "cheaper" Monaco to sell or get some profit from, it makes sense to me that they would make watches for such partners that could be sold more cheaply without sullying the Heuer Monaco brand image.

And that some of the blue/blues with painted markers feature a similar shonky Heuer shield to some of the above only adds to those concerns:

If we accept that as genuine, does that mean we also have to give the nod to dials with waffle markers?

To be honest, I think whether these were genuine Heuers or some dials bound for Edox/Diarex/Bucherer were intercepted/diverted when still sterile is quite possibly lost to the mists of time. And somebody like M. Racine is undoubtedly advising in good faith. But the acid test would be, are you willing to invest your own money in one? And for me, with too many questions hanging over them still, the answer would be no. Someone else's answer might differ and they have every right to come to that conclusion, but I would urge them to go over all the information we do have before coming to that result.