The Black Prince, a beautifully turbid true-black opal weighing 60.46 carats, was the top lot at Bonhams' California opal sale on December 11, selling for $134,500. The precious stone, which boasts an incandescent, hologramatic patina, was given a presale estimated value of $120,000 to $150,000.
Although opals are thought by some to be unlucky, the strong sale result is a further boost to the buoyant jewellery market; Barclays' 2012 Wealth Insights report concluded that jewellery is the most popular of any treasure asset.
Following the sale, Claudia Florian, co-consulting director of Bonhams' natural history department, commented: "Distinctive mineral specimens, opals of all hues, gold nuggets, lapidary works of art and gemstones were the true highlights of the holiday natural history auctions at Bonhams."
Competitive bidding brought in excess of $2m, with items from the esteemed collection of Margie and Robert E Petersen, such as a 25.31 ounce gold nugget, performing well.
The large gold nugget, which was given a pre-auction estimate of $50,000-$60,000, sold for $68,500 - representing a 14.2% increase on the high valuation. The nugget, which is capable of standing unsupported, is thought to have originated in Alaska.
The Petersens were avid collectors whose interests spanned categories including firearms, wine and classic cars.
Many of the other treasures on offer had been discovered in exotic locations and retrieved from mines and shipwrecks, including the 17th century Atocha - one of the most illustrious "treasure ships" ever to be salvaged.
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