106 GENERAL CHARACTERS OF PRECIOUS STONES 



gave results which closely approximated to market prices ; since the discovery of the South 

 African diamond-fields, however, large stones have come into the market in much gi-eater 

 numbers than previously, so that even this rule is no longer applicable for trade purposes. 

 The subject of price will be again referred to when we come to treat specially of diamonds 

 and other precious stones. 



We must now consider the relative value of cut and uncut stones. A cut stone will 

 naturally be more expensive than a rough stone of the same quality and size. To the value 

 of the rough stone must be added the cost of cutting ; and this, especially in the case of the 

 harder stones, and most of all in the diamond, is very considerable. Fuithermore, a 

 considerable portion, often one- half or more, of the material of the rough stone is lost in the 

 process of cutting ; a cut stone is, therefore, in its rough condition, often double the weight 

 of the same stone when faceted, and this larger weight is taken into account when the stone 

 is sold. 



The particular form in which a stone is cut is also an important factor in determining 

 its price, since the cutting of more complicated forms with numerous facets is more 

 expensive than that of simpler forms with fewer facets. Thus the price of a rose diamond of 

 the best quality is only about four-fifths of that of a brilliant of the same weight and quality. 



The value of a precious stone varies to a very great extent according as the features on 

 which its particular beauty depends are strongly marked or insignificant ; and in this 

 connection small differences of quality, scarcely noticeable to an unpractised eye, are all 

 taken into account. A diamond of the second water, cut in the form of a brilliant and 

 weighing one carat, is usually considered to be two-thirds the value of a similar stone of the 

 first water. Further information of this kind may be obtained from the table published in 

 1878 by Vanderheym, which is given below in the section dealing with the value of 

 diamonds. The presence or absence of the various faults to which precious stones are liable, 

 and which have been already considered, of course affects the value of a stone to a very 

 large extent, the presence of a large number of faults sometimes rendering an otherwise 

 costly stone absolutely worthless. 



III. CLASSIFICATION OF PRECIOUS STONES. 



In the present section we propose to consider the various systems of nomenclature and 

 classification adopted for precious stones. 



In scientific mineralogy, precious stones are regarded simply as minerals and are 

 classified accordingly. The classification of precious stones adopted by jewellers, however, is 

 more or less arbitrary in nature and differs somewhat widely from the system used by 

 mineralogists. Both scientific mineralogists and dealers in precious stones nevertheless 

 agree in bringing together as of one kind all those stones which resemble each other in their 

 essential characters, and in distinguishing by a special name the stones of that kind from 

 those of another kind. In arranging precious stones into such kinds, the characters which 

 are considered essential by a specialist in jewels may not be so considered by a mineralogist ; 

 and, conversely, what a mineralogist considers an essential feature may not have the same 

 importance in the classification of a precious stone specialist. From the mineralogical point 

 of view, a species is defined by the chemical composition and the crystalline form, together 

 with the several physical characters of the stones it embraces. These characters must be 

 constant for the same species, or at least vary within certain limits in a certain definite 



