This was bought for research purposes

it's not really my thing and I now have a cut overlay vase that I particularly love, so this one possibly isn't going to be staying any longer but I would like to know something about it.
The base third of this is pale blue glass, the top two thirds have a thick deep blue overlay on, which is cut through to clear.
So... how was this made? Was the whole thing clear, cased pale blue, cased dark blue and then cut to pale blue on the bottom third, but cut through the dark blue and pale blue to the clear on the top third?
Is this what is called Intaglio? It is very deep cutting as far as I can see.
Date wise, the flowers are stylised and look art nouveau to me. Would that fit?
Any thoughts on who may have made this would be gratefully received. I have assumed Bohemian. From the minute amount of knowledge I have and looking at others around on the net, it looks quite a good one?
The base is polished flat and it measures 11.5cm tall (4 1/2") x 13cm diameter (5 1/4")
thanks in advance for any help.
m