Last Updated: Nov 21, 2016 Views: 94
My apologies for not being able to answer your question more quickly. In the many years that I have worked with our Steuben-related archives, I have never seen actual production statistics nor dates of manufacture for individual pieces, unless it is a very special piece, as a limited edition. (This is generally true for all glass companies - it is almost impossible to find the date when the last piece of a line was made.) The Trillium bowl was part of the standard/stock line. As you know, it was designed and first sold in 1958. It was shown in their catalogs through 1970; it does not appear in the 1971 catalog, but this may mean that they were just not featuring it, and giving "space" to the newer items.
I am sorry that I cannot help you further, but I am sure the couple will be pleased with your thoughtfulness to receive a piece of Steuben glass, which has been given as wedding and presidential gifts throughout its history.