(The), or “The Diamond Challenge Sculls” of the Henley Royal Regatta, are a pair of crossed silver sculls not quite a foot in length, surmounted by an imitation wreath of laurel, and having a pendant of diamonds. They lie in a box lined with velvet, which contains also the names of all the winners. The prize is rowed for every year, and the sculls pass from winner to winner; but each winner receives a silver cup, which becomes his own absolute property. Established 1844 by the Royal Regatta Committee.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894