19(5 On Gan.r. 



ca-Jt in the body of the stone, which may be discovered by 

 holding it against the hght, the stone will prove good. 



It often happens that a stone shall appear of a reddish 

 hue on the outward coat, not unlike the colour of rustv 

 iron, yet by looking through it against the light you may 

 observe the heart of the stone to be white ; and if there be 

 any black spots, or flaws, or veins in it, which by a true eye 

 may be discovered, although the coat of the stone be opake, 

 such stones arc generally good. 



If a diamond appear of a greenish bright coat rcsembling^ 

 a piece of green glass inclining to black, it generally proves 

 hard, and seldom bad : such stones have been known to be 

 of the first water : but if any tincture of yellow seems to 

 run with it, you mav depend upon its being a bad stone. 



All stones of a milky coat, whether the coat be bright or 

 dull, if ever so little inclining to the blueish cast, are natu- 

 rally soft, and in danger of being flawed in the cutting ; 

 and though they should have the good fortune to escape, 

 yet they will prove dead and milkv. 



All diamonds of a cinnamon-coloured coat are very du- 

 bious ; but if of a bright, mixt with a little green, then they 

 are certainly bad, and are accounted amongst the worst of 

 colours. 



The greatest care must be taken to avoid beamy stones ; 

 and this requires greater skill and practice than many jew- 

 ellers are equal to. By beamy stones are meant such as look 

 fair to the eye, and vet are so full of veins to the centre that 

 no art or labour can polish them ; they run through several 

 parts of the stone, and sometimes through all : when they 

 appear on the outside they show themselves like protuberant 

 excrescences, from whence run innumerable small veins 

 obliquely crossing each other and shooting into the body 

 of the stone : the stone itself will appear a very bright coat, 

 and shining, and the veins looking like a very small po- 

 lished steel needle ; sometimes the knot of the veins will 

 be in the centre, and fibres shoot outward, and the small 

 ends terminate in the coat of the diamond ; stones having 

 these properties are difficultly cut, and will never take a good 

 polish. 



There are diamonds of almost all colours : some incline 

 lo rose colour, others to green, blue, brown, and black. 

 Mr. Dutens saw a black diamond at Vienna in the collec- 

 ti(jn of the prince of Lichtenstein. 



The diamond becomes phosphoric by exposure to the solar 

 rays, or by hcatmg, it red hot in a crucible on the fire» It 



is 



