One of the first Heuers I bought off the internet had a "17 jewels" marking.
When I asked Jeff about it he said "I'm not so sure" (this was very early days of on the dash, with much less known and researched) "but I don't thing Heuer ever had a number of jewels on the dial".
Many (seven?) years later I still haven't seen a trustworthy Heuer with jewel number on the dial. So I think the rule still holds good.
BTW: I returned the watch to the seller (one of the early vintage watch sellers on the internet) and after a lot of grumbling about "those forum know it alls" returned my money, of course minus a 15% "restocking fee". The 15% loss at least cemented the lesson!