JUNEAU, ALASKA (AP) – A gemstone, billed as one of the largest gem-quality opals in existence, was sold for USD143,750 at auction in Alaska on Sunday. The opal, dubbed the ‘Americus Australis’, weighs more than 11,800 carats, according to the auction house Alaska Premier Auctions & Appraisals. It also has a long history. Most recently,
