Horatio Alger 
Paul the Peddler (Illustrated) 
Or, The Fortunes of a Young Street Merchant

The pawnbroker saw that he had made a mistake. Paul was not as much in need of money as the majority of his customers. He would rather pay twenty dollars than lose the bargain, though it went against the grain to pay so much money. But after pronouncing the stone an imitation, how could he rise much above the offer he had already made? He resolved to approach it gradually. Surveying it more closely, he said: ’It is an excellent imitation. I will give you five dollars.’ Paul was not without natural shrewdness, and this sudden advance convinced him that it was, after all, a real stone. He determined to get twenty dollars or carry the ring home.