Sotheby’s London Auction
By Rubina Posh June 16,2017
A 1937 Art Deco Design Cartier Diamond Brooch set with round brilliant cut and baguette diamonds, warn by Margaret Thatcher, had an estimated value of £25,000 – £35,000 (AUD$42,320 – $59,248)
On 7th June at the Sotheby’s Fine Jewels Auction in London, this brooch was sold for £81,250 (AUD$137,540)
http://www.sothebys.com/en/auctions/ecatalogue/2017/fine-jewels-l17051/lot.363.html