I am "lovely guy who posted the ID" of this piece of glass. Hi everyone...
I have full confirmation that this piece of glass designed by Dragan Drobnjak, somewhere in the period 1970-1986.
Dragan Drobnjak is born 1941, and completed the school for sculptors. He was leading designer of the factory "9. October" from Prokuplje (Serbia) beetween 1969-1991.
Factory in Prokuplje was founded by Serbian glass factory in 1962, as their outpost. Later glassworks became independent and functioned to bankruptcy 2003.
During the 19th and 20th century in Serbia worked 10 glassworks.
if anyone has any questions I will gladly answer.