“The Adventure of the Beryl Coronet” is one of the 56 short Sherlock Holmes stories written by British author Sir Arthur Conan Doyle. A banker, Mr. Alexander Holder of Streatham, makes a loan of £50,000 to a socially prominent client, who leaves a beryl coronet — one of the most valuable public possessions in existence — as collateral. Holder feels that he must not leave this rare and precious piece of jewellery in his personal safe at the bank, and so he takes it home with him to lock it up there.