E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The King of Ceylon has the finest ruby ever seen. It is a span long, as thick as a mans arm, and without a flaw. Kublai-Khan offered the value of a city for it, but the king answered that he would not part with it if all the treasures of the world were laid at his feet. (Marco Polo.)