As noted in the article, it was sold for £10,000 at Sotheby’s on July 16, 1931, where it was bought for Mrs Harkness by Edgar Bluett.
Mrs Harkness was a fairly regular visitor to Bluetts when she visited London in the 1920s-30s. The sale caused considerable press interest.
The following is from the Daily Express, July 17, 1931:
The famous Canning Jewel, gift of a Florentine prince to a Mogul emperor of India, and the property of the Earl of Harewood, fetched £10,000 when put up for sale at Sotheby’s yesterday. The bidder was Mr Bluett of Davies-street, W., and he was acting on behalf of a wealthy American woman… Only five minutes was allowed for the sale and the auctioneer announced that unless £10,000 was offered the jewel would be withdrawn from the sale. Four minutes passed in silence and then Mr Bluett, with a nod of his head, signified the bid – the only offer.
Bluetts charged Mrs Harkness a commission of £220. I recall a letter, on Claridges notepaper, from Mrs Harkness to Edgar Bluett, thanking him for acting on her behalf.