Lot 71. A mid 19th century enamel and rose-cut diamond-set cyrillic 'N' for Tsar Nicholas I,  bangle. Estimate GBP 20,000 - GBP 30,000 (USD 26,560 - USD 39,840). © Christie's Images Ltd 2017

The octagonal plaque with applied rose-cut diamond-set cyrillic 'N' for Tsar Nicholas I (reigned 1825-1855) beneath a similarly-set coronet on a cobalt blue enamel ground to a two-tiered rose and old-cut diamond cluster border and further elaborately chased hinged bangle half decorated with blue guilloché enamel, plaque circa 1840, bangle circa 1860, internal diameter 5.1cm, mounted in silver and gold.

Tsar Nicholas I from a portrait miniature by Iwan Winberg