218 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



tory instead of being dug out of the earth; all other makeshifts being 

 properly described as l 'imitations." The production of imitation gems 

 is by no means a modern invention, as is doubtless well known to you. 

 To go no further back than the time of the Roman Empire, the master 

 glassmakers of the dawn of our era, whose skill and knowledge of glass- 

 making one appreciates more highly the more one investigates the 

 industrial life of those times, were able to imitate almost any precious 

 stone exactly, as far as outward appearance went, in colored glass — 

 and not only the transparent gems, but the structure of such semi- 

 precious stones as agate, cornelian, lapis, and porphyry. It would be 

 quite out of place to devote any time to-night to this historical aspect 

 of imitation gems, but I can not refrain from alluding to the remark- 

 able examples of such imitations found by Mr. Woolley at Karanog, 1 

 from winch it is difficult to resist the conclusion that in quite early 

 times Nubia was the center of this industry. To judge by the stories 

 one reads about jewels in those times — stories of the Emperor Com- 

 nenus, for example — one suspects that the glassmakers turned their 

 skill in this direction to some account and considerable profit on behalf 

 of an ignorant and somewhat credulous aristocracy; for in those days, 

 and, in fact, until quite recently, not only was the nomenclature of 

 gems very vague, but methods of identification were chiefly remarkable 

 for their nonexistence. 



The chief criterion of a precious stone was its color, so much so that 

 throughout medieval times blue glass was known as sapphire and 

 green glass as beryl, etc., giving rise to the legend that in the time of 

 Queen Elizabeth windows were glazed with sheets of beryl. 2 As the 

 tendency still lingers to regard all red stones as rubies and green as' 

 emeralds, and so on, I would like to make it clear at this point that; 

 color is really quite an accidental property of precious stones; the' 

 substance of which nearly every species of transparent gem is essen-' 

 tially composed is coiorless, and the color is really produced by minute 

 proportions of impurity. 



This being the case, we find that on the one hand the same species of 

 gem stone may exist in a large variety of colors, and on the other hand 

 that a color characteristically associated with one gem may often be 

 found in another having essentially different composition and prop- 

 erties. Owing to this confusion it was very difficult to draw the line 

 between a genuine and imitation stone until the various species of gem 

 stone were accurately defined and their names clearly associated with 

 particular composition and properties, the determination of which 

 forms at the present time a means of distinguishing one from another, 



i Karanog, by C L. Woolley and D. Randall. Maclver: Philadelphia Museum, 1910. 



2 This is quoted in Hollingshed. We read in Theophilus (II, cap. xii) of "tabulas saphiri pretiosas ac 

 satis utiles in fenestris." In a previous paper (Journal, Mar. 15, 1907) I have shown how the name jet was 

 variously applied. 



