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They make substantial sums whenever they appear on the market.

On September 23 the Toulouse branch of the Ivoire group of auctioneers will be offering a 4in (10cm) high beige steatite rectangular seal of square section with a top carved in the shape of a mountainous landscape.

Discovered in the possession of a local family and identified by the Asian art expert Pierre Ansas, the seal is one of the highlights of Ivoire Toulouse-Primadeco’s Asian art auction, where it carries an estimate of €500,000-600,000.