A highlight of the upcoming Americana Week 2010 sales at Christie's in New York is a rare personal keepsake that belonged to one of America's most revered presidents, Thomas Jefferson. Conceived as a memento mori, the keepsake is an engraved gold watch key containing a braided lock of hair from Jefferson's wife, Martha Wayles Jefferson, who died at age 33. A devoted watch collector, Jefferson likely commissioned the watch key as a poignant reminder of his young wife in the years following her death. It is estimated to sell for $40,000 to 80,000.