The House with the High Wall by Arthur Gask

IT WAS upon a Monday night that Robert had returned home to his little flat in Ensum Street with the necklace, and in the first flush of his success all prospects seemed rosy ones.

The possession of the necklace was the greatest thrill that he had experienced in all his life, and in the next few days he was never tired of looking at it. With loving care he had cleaned it with a tooth-brush in tepid soapy water, so thoroughly that, so far as he could see, hardly any speck of dirt could be found anywhere in the setting of the stones, and, with a piece of chamois leather, he had spent hours polishing it up.