While checking some dial plates regarding their authenticity I've found finally a proof for the EGGLI-WEIBEL hallmark.
An earlier superb post form Stefano Mazzariol shows amongst others this hallmark labeled METELEM (correct producer name is METALAM):
Follow link :Producers of dials for Rolex
This information has been of some interest because it's a logo often seen on gilt dials, and it has been taken as fact until 2013 when the sign has become interpreted as more likely from EGGLI-WEIBEL:
Read Story :GMT exclamation mark dial precision
But I think there has not been a proof so far (the pics in the thread have gone, so not sure about the former content). Anyway, please check this eBay offer below (still open for interested parties) - here you see a dial sample etui labeled with LS. (for Louis) EGGLI-WEIBEL Co. SA BIENNE and further down the EW logo on the backside of a dial:
follow link: Boîte de cadran emailles pour montre LS EGGLI WEIBEL Suisse
So this logo on Rolex dials is 100 % EGGLI-WEIBEL.
Not sure about a METALEM logo on a Rolex dial, probably they didn't make any (?), it would show very likely an M only, like here:
Last but not least another interesting labeled EW dial for Rolex, found here (but I’ve never seen that on a gilt dial):
Read more: rolex oyster date 6694 few things I've never seen before
Thanks for reading,
Xeramic