AKBOX AND ITS COMPOUNDS. 25 



upon the weight, the purity, and the color. A diamond 

 which, after being cut, weighs one carat, is worth com- 

 monly 8. The price increases largely with the size, for 

 one weighing four carats would be worth 128, and one 

 often carats would be 800. When we get up to twenty 

 carats the prices rise much more rapidly. The Regent 

 diamond is estimated at 125,000. 



34. Cutting of Diamonds. The art of cutting and pol- 

 ishing diamonds was unknown till 1456, when it was dis- 

 covered by Louis Berquen, of Bruges. The process is 

 thus described by Professor Dana. " The diamond is cut 

 by taking advantage of its cleavage, and also by abrasion 

 with its own powder, and by friction with another dia- 

 mond. The flaws are first removed by cleaving it, or 

 else by sawing it with an iron wire, which is covered 

 with diamond powder a tedious process, as the wire is 

 generally cut through after drawing it across five or six 

 times. After the portion containing flaws has thus been 

 cut off, the crystal is fixed to the end of a stick, in a 

 strong cement, leaving the part projecting which is to be 

 cut; and another being prepared in the same manner, 

 the two are rubbed together till a facet is produced. By 

 changing the position, other facets are added in succes- 

 sion till the required form is obtained. A circular plate 

 of soft iron is then charged with the powder produced 

 by the abrasion, and this, by its revolution, finally polish- 

 es the stone. To complete a single facet often requires 

 several hours." The expense of cutting the Regent dia- 

 mond was estimated at 5000 sterling, and the mere fil- 

 ings at 7000 sterling. 



35. Uses of the Diamond. The most familiar use of 

 the diamond is cutting glass. It is also used for lenses 

 in microscopes. Diamonds that can not be worked are 

 sold under the name of bort, for various uses. Splinters 

 of bort are made into fine drills for drilling artificial 

 teeth and gems of various kinds. 



36. Localities of Diamonds. Diamonds are found in 



B 



