Mary Curtis
One of the Curtis clan, can't find more information about who she is other than she is not Mary Bernard Curtis, who is Mrs. Frank Gardner Curtis. She is also not the impressionist painter.
Update: 11/5/2020 -
Rosella Mamoli Zorzi in her article ["'Foresti' In Venice in the Second Half of the 19th Century: Their Passion for Paintings, Brocades, and Glass." Atti dell' Instituto Veneto di Scienze, lettre ed arti (Venice, 2016)] describes this Mary Curtis as the sister of Daniel Sargent Curtis, who is Mary Frazier Curtis (1827-1890). She doesn't give a citation for this, but she does reference letters from Daniel Sargent Curtis to his sister and his private diaries so it seems likely that she is correct, excepting that Mary Frazier Curtis died in 1890 and the Venetian goblet C11s21 was made for the rededication of the Campanile in 1912. Below are the manuscripts Rosella read for the article.
Manuscripts
Curtis. Ms. Marciana Rari Tursi. 449. Curtis letters. 635. Marciana, Rari Tursi 635 1/1.15; letter of D.S. Curtis to his sister Mary, from Venice, 7 July 1879. Curtis. 1892. Curtis, Daniel Sargent. Unpublished Diary for 1892. Private collection. Curtis. 1894. Curtis, Daniel Sargent. Unpublished Diary for 1894. Private collection. Curtis. 1895. Curtis, Daniel Sargent. Unpublished Diary for 1895. Private collection.