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.
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.