Diamond. 
392 
blocks, thick enough to be held in the hand. The 
powder which is rubbed oft the stones in this opera- 
tion is caught in a little box provided for the pur- 
pose, and afterwards used to grind and polish the 
stones. From the extreme hardness of these stones, 
it has been alleged that rubbing them against each 
other is the only way to reduce them to an impal- 
pable powder ; but this is not strictly the case, as 
the jewellers are in the habit of pounding small 
pieces in steel mortars fitted with a pestle exactly 
the size of the interior, so that none of the diamond 
can escape. A few blows with a hammer upon the 
head of the pestle completely powder the stone. 
Diamonds are more or less valuable, according to 
what is called their water. Those of the first water 
are in the greatest degree of purity and perfection, 
while those of less brilliancy are said to be of the 
second or third water, and thus they proceed till the 
stone becomes coloured ; for there are diamonds of 
all colours, though faintly tinted. Thus we have 
some of a rose colour ; others green, blue, brown, 
black ; and some are marked with black spots. 
