People spend lots of money buying fine quality precious gems, but then don’t clean them regularly. The gems then lose their sparkling lustrous appearance. With precious stones, a dirty stone can appear much lower in quality than it really is, as grime builds up on the surfaces of the gem.
At the Christies ‘Magnificent Jewels Auction’ held in Geneva on May 15th 2013 the world’s largest ‘flawless’ and ‘colourless’ diamond ever put up for auction was sold for a record 25.9 million Swiss Francs (US$26.7 million). Christies were hoping to realize up to US$30 million.