In 1850, the legendary Koh-i-noor diamond, gem of Eastern potentates, was transferred from the Punjab in India and, in an elaborate ceremony, placed into Queen Victoria's outstretched hands. This act inaugurated what author Adrienne Munich recognizes in her engaging new book as the empire of diamonds. Diamonds were a symbol of political power--only for the very rich and influential. But, in a development that also reflected the British Empire's...