Vetreria Etrusca Charger/Platter of Unknown Age

This is one I don't know much about. I know my mother got it for me about 30 years ago, but have NO idea how old it might actually be. Some she purchased for me new, others were finds she had made. The form is interesting in that it's made of a continuous spiral of round glass 'tubing'. The underside is ridged, but the upper surface is smooth with a slight raise around the edge. The color on this one is a wonderfully rich, deep cobalt that was a real pain to photograph! If you have any idea what year this piece might have been made, I'd appreciate hearing from you. It is just under 17 inches across.