Stems were purchased in the mid 1960s. The company which currently sells Carlo Moretti glass responded to my inquiry on these stems with the following note.
"I can only confirm for you that this glassware was manufactured by Carlo Moretti from 1959 to the early 1960s. I can also definitely advise you that in our warehouses we no longer have any of these pieces - they have been out of production for more than 40 years. Your only chance of finding replacements is in ebay since periodically they do come up there."