Two factors determine how a piece of jewelry will perform at auction: Its intrinsic value coupled with its provenance (the paper trail documenting who made or owned it).


In the case of the 17.21-carat Kashmir sapphire that leads Bonhams New York Jewels sale on Dec. 7, it’s impossible to say which factor is more impressive.


While a Kashmir of any size is considered rare (production at the mine, located in the Himalayan region between India and Pakistan, peaked in the late 1880s), a stone of 17+ carats is exceptional. Add a “royal blue” hue—as deemed by Gübelin Gem Lab, a worldwide authority on colored stones—into the mix and the cushion-shaped gem is guaranteed to fetch top dollar.


Then there’s the provenance. Owned by the Smith family of Vermont for more than a century, the jewel was acquired by Edward Curtis Smith, the governor of Vermont, for his wife, Anna Bailey James Smith, shortly after the turn of the last century. (His father, Gov. J. Gregory Smith, was one of the founders of the Northern Pacific Railway, while his mother, author Ann Eliza Smith, was descended from Vermont Senator Lawrence Brainerd, a prominent figure in the Underground Railroad.)
17.21-carat Kashmir Sapphire and Diamond Brooch

17.21-carat Kashmir Sapphire and Diamond Brooch Courtesy of Bonham's


Set in a belle époque platinum brooch, c. 1910, and framed by four diamonds, including two table-cut pear-shape gems totaling 4 carats, the piece is expected to fetch between $500,000 and $800,000.


Emily Waterfall, Los Angeles head of jewelry for Bonhams, said the consignor “remembers her mother wearing the brooch ‘everywhere,’” from Nixon’s inauguration to the grocery store.