Hello Ken,
More photos of the bowl and label would be helpful.
If you can take a close up of the lines going through it, and of the label, that would be great.
Also, if it is fact that the piece was bought in 1959, it would be an increadible help to have that photo of the label. Not sure if you saw but there is a Labels thread that is ongoing, and we are trying to document Murano labels and any info on them we can. To have a such a specific date to go along with a label will help many.
Thanks
Javier