Answered By: Regan Brumagen Last Updated: Feb 06, 2017 Views: 22
From Dr. Robert Brill, Research Scientist Emeritus:
We analyzed a fragment of Tiffany favrile glass. It turned out to be a high-lead glass. The composition was approximately 57.3% SiO2, 38.7% PbO, 3.1% K2O, + some trace elements.
I would estimate that the index should be ~1.61.