Although similar to Jaffa, I do not believe this to be an example of that decor. I have located images of Jaffa in several different glass forms and ages, both on line and in my Lalique books, IMHO the pattern is different from this piece.
I can not find an example of Jaffa that has any form of stem on it such as these do. All examples I found have a curved bottom. I have also observed that the indentations into the center of the design appear on this to be more or less raised lines or ridges that decrease in height the further from the edge they protrude (could be the camera angle). On Jaffa, the indents are quite pronounced and in a triangular looking form. (kind of like saw teeth).
Additionally, the top portion of the pattern is in almost all cases a semi circle and this appears a little more jagged. (again, could be camera angle). I did find a contemporary votive with a similar top of the pattern and the lines protruding from the top of the pattern to the rim of the glass, but that piece has pretty pronounced triangular "teeth" as part of the pattern.
Also, your comment regarding the use of the R Lalique signature is accurate, as the signature usage was stopped in 1945 when Rene Lalique passed away, but was used up until that time.
I am interested in what Mike will have to say....
Craig