392 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



worn as a gem, although, being opaque, small scratches are less noticeable than in 

 transparent stones. 



Whether the ancients were acquainted with turquoise is doubtful, but the stone was 

 certainly known in the Middle Ages. Its use as a gem is very general at the present time, 

 the stone being as much prized in Eastern as in Western countries. Especially in the East, 

 in Turkey, Egypt, Arabia, and Persia, it is much worn, being regarded by Orientals as a 

 lucky stone. Thus it is to be met with everywhere in these countries, if only as a fragment 

 of poor quality set in tin. It is much used in the decoration of the handles and scabbards 

 of daggers and swords and of the trappings of horses and for other similar purposes. The 

 name turquoise is said to signify Turkish gem. In Western countries large turquoises are 

 frequently mounted with a border of small diamonds, while small stones form an effective 

 frame for certain other precious stones of large size. 



As is usually the case with opaque stones, turquoise is nearly always cut en cabochon 

 with a plane undersurface of circular or oval outline (Plate XX., Fig. 2). Exceptionally 

 large and fine specimens are said to be sometimes cut as table-stones or as thick-stones ; but 

 since the existence of facets does nothing, on account of the opacity of the stone, towards 

 enhancing its beauty these forms of cutting are but rarely adopted. The turquoise is often 

 engraved with various devices ; in the Orient, for example, with quotations from the Koran, 

 the letters being filled in with gold. Stones which are intended to be engraved are often 

 cut with a flat instead of a rounded surface. 



This precious stone, which is so generally prized, has a very considerable value, and in 

 the Middle Ages was worth even more than now. The price of single stones varies with 

 their size and their colour, the most valuable being of a pure sky-blue colour uniformly 

 distributed and free from patches. As the colour inclines more and more to green the stone 

 becomes less and less valuable ; while with regard to size, small turquoises are abundant 

 and consequently cheap. Pieces of turquoise the size of a pea are rare, and when of a good 

 colour command a high price. Small stones are bought and sold in thousands, rather larger 

 specimens in dozens, while those above a certain size are sold singly. A carat stone of the 

 best quality may be worth about fifty shillings, but the price of larger stones, owing to 

 their rarity, is not in the same proportion to their weight. In the case of rough specimens 

 it is very essential that they have a certain thickness, so that when cut en cabochon they 

 shall not be too thin and flat, as is the case when the turquoise forms only a thin layer 

 on the matrix. 



Large turquoises of fine quality are few in number. Among such may be mentioned 

 a heart-shaped stone 2 inches in length, which some time ago was in the possession of 

 a Moscow jeweller, and which had been formerly worn as an amulet by Nadir Shah: an 

 inscription from the Koran is engraved on it in gold, and it is valued at 5000 roubles. 

 A turquoise in the collection of the Imperial Academy at Moscow measures more than 

 3 inches in length and 1 inch in breadth. The largest and finest stone in existence is said 

 to be one in the treasury of the Shah of Persia. The most important turquoise mines 

 known are situated in the dominions of this monarch, by whom the finest stones were 

 formerly appropriated. 



With regard to the occurrence of turquoise in nature it has been stated already that 

 the mineral is found in veins of greater or less extent (Plate XX., Fig. 3) in certain rocks, 

 having been deposited from aqueous solution in the cracks and crevices of these rocks. 

 When the cavity is incompletely filled the turquoise forms a thin crust on its walls, and the 

 surface of the incrastation may be mammillated, botryoidal, stalactitic, &c. The mother- 

 rock of turquoise differs at different localities ; thus at one place the matrix may be 



