la donnée des procédés

10:12 Jul 28, 2017 

donnée used in the singular can have this meaning: Ce qui est connu et admis, et qui sert de base, à un raisonnement, à un examen ou à une recherche (http://atilf.atilf.fr/dendien/scripts/tlfiv5/advanced.exe?8;... Also: Le point sur lequel on fonde un raisonnement, et qui est reconnu. (https://www.littre.org/definition/donnée). Perhaps something like '[No foreign influence/origin.] On the contrary, they're at the heart of/the starting point for those techniques...'? OR 'It is admitted/We know that they're at the heart...]'? Just suggestions as to what it might mean - I'll leave you or others to choose the right words.

21:10 Jul 27, 2017 

OK, thanks, that sort oa mkes more sense now...
So there's no concrete proof this type of mirror is the result of foreign influence; however, they are consistent with the processes [known in Egypt] — I think if you try and work along those lines, you should be able to come up with soemthing...

21:00 Jul 27, 2017 

MIROIRS EN VERRE ÉTAMÉ. - Les miroirs en verre étamé n'apparaissent pas avant l'époque chrétienne, sans toutefois qu'on puisse affirmer qu'ils soient dus à une influence étrangère. Thank you!

20:36 Jul 27, 2017 

First of all, we badly need the preceding context: what are 'ils', and why are they 'au contraire' whatever has gone before.

I suspect 'donnée' here has its sense of details / particulars, and 'procédé' is process' rather than 'technique' — I suspect (but without that context, can't be sure) that the writer is saying "they go into details about the processes..."

By the way, I wouldn't say 'fake' — that sounds like some deliberate attempt to deceive! This is more like 'costume jewellery', so perhaps 'artificial' or 'imitation'?