Method for high clarity plique à jour I notice that Laliques famous plique à jour pieces have remarkable clarity.

Typical modern works, or those examples I see being done by artisans on YouTube are always much more cloudy or translucent.

How is that Lalique was able to get such pure transparency in his cells?
This is completely a guess on my part...but I know that when I was taking a jewelry design class in the early 1990s, my instructor had to eliminate the enameling section of the class because the "ingredients" and techniques had just been determined too toxic to teach, and she hadn't worked with the new resins enough to be comfortable teaching with them.  

So, maybe the big difference is our current scientific knowledge about the levels of toxicity that limits our access to the same raw materials that Lalique was using.