The number of writers on precious stones from the thirteenth to the nineteeth century is very large, but little original
knowledge was added to what was previously known, from the
time of Pliny, in the first century, to the Arabian writers
between nine and ten centuries later. Ibn-Sina, better known
as Avicenna, a celebrated Arab philosopher and physician, 9S01037 A. D., who is said to have anticipated the discoveries of
modern science, wrote on the subject of precious stones ; but
Älohammed Ben Mansur, of the twelfth century, was the first
after Pliny to compose a scientific treatise on gems, which he
dedicated to the Shah of Persia. His knowledge, thinks Mr.
King, was marvellous considering the age in which he lived ;
he was actually in advance of all other writers of his time, and
equal to Haiiy, Mohs, and others in their supposed discoveries
several centuries later.
Michael Constantius Psellus, a writer of the eleventh
century, composed a work on the "Virtues of Stones," in
which he promulgates a knowledge of their medicinal uses ;
Jerome Cardan, 1501-1576 A.D., divided all gems into three
classes : first, brilliant and transparent ; second, opaque ; third,
compound. He advanced the theory that diamonds and
opals originated from gold, sapphires and rubies from silver,
and carbuncles, amethysts, and garnets from iron. A work
on precious stones, " De Lapidibus et Gemmis," composed
by De Boot, or Boethius, is regarded as an example of a
remarkable combination of "varied learning and absurd
credulity."
/ Mystical Powers. — Frequent allusions to the popular belief that precious stones are endowed with supernatural
powers, and that they exercise some mysterious influence
on the fortunes and destiny of individuals and communities,
met with in ancient, mediaeval, and modern literature, renders
