Thanks everybody.
Clickklick: Yes I'm keeping it for myself. Since the bowl is rather big I wanted to keep an hefty stem, but,as you suggest I could give a more clean line. The main defect is the upper junction between the shank and the bowl: here I sanded deeper than I wanted. After if I aligned every part the stem and the shank would become, IMHO, too thiny front of the bowl. So I preferred a general proportion to a cleaner work.
Thank you for your remark about the dangers for the bowl. After reading yor words I tried to measure that spot and I think it's about 7 mm. thick.