It isn't known when and where it all began, but throughout the ages and in the most diverse of all societies, precious stones have held an almost mystical power and significance. They shone round the necks and embellished the fingers of the ancient Egyptians; they gleamed from the turbans of great Mogul emperors and they were centrally the myth of the Holy Grail. From the earliest times, precious stones have gained a value far beyond and rational assessment of their worth. Some of the best-known gems were deemed so valuable that they financed large armies; others led men to torture and murder, or literally changed the destinies of whole countries.
Precious stones are of much value for man as _____.