Belle Epoque Platinum, Freshwater Button Pearl and Diamond Bar Brooch. Photo courtesy Doyle New York.

The pierced elongated oval mount centering one button pearl approximately 9.20 x 6.10 mm., set throughout with 94 old-mine cut diamonds approximately 7.60 cts., circa 1910, approximately 12.2 dwts. Estimate $5,000-7,000 

With GIA report no. 17207542 stating that the pearl is natural, freshwater, no indications of treatment. 

Doyle New York. Important Jewelry. Wednesday, September 25, 2013 at 10am - http://www.doylenewyork.com