Huge and absolutely fantastic glass vase, 1970s

Huge and absolutely fantastic glass vase. So well made and beautiful. I have been told that it is either a Kosta Boda or a Kaj Franck, but I have not been able to find this model. One thing is certain, it is very professionally made. 37 cm high, 13 X 7 cm in length/width and weighs a full 4550 grams. Several layers of glass in transparent, blue colours and shades. It has no chips, cracks or similar, but has a little ‘lime/glass pest’ in the lower part of the vase, after having contained water for many years. Will be packed securely and sent with insurance.