The same museum of my posting of yesterday had also an exhibition of the glass works of René Lalique. The famous french glass designer ( also a gifted jeweller) from the art nouveau and art deco period in france.
It is for sure worth a visit.
The dragonflies look real but are just engravings in glass. Lalique made mass production from highly designed glass possible with his own glass factory in Combs-la-Ville in 1909 by using a kind of crystal glass with 12% lead oxide ( normally 24% is used) and metal malls. The growing of the perfume industry with their glass bottles was a great help as one of the main designers for these. They must have a highly distinctive appearance and still be payable in mass production.