THE DIAMOND 81
light,
called its fire, it stands pre-eminent. It possesses a considerable
variety of colour ; that regarded as the most perfect and rare is the
blue-white colour. Most commonly, however, the colours are clear, with
steely-blue casts, pale and neutral-colour yellow, whilst amongst the
most expensive and rare are those of green, pale pink, red, and any
other variety with strong and decided colour. Although these stones are
sold by the carat, there can be no hard and fast rule laid down as to
the value of a carat, for this depends on the size, quality, and the
purity of the stone. The larger the stone the greater the value per
carat, and prices have been known to range from 25l per carat
for a small stone to 5007. per carat for a large one, whereas the
exceptionally large stones possess a value almost beyond estimation.
It
often happens that some stones—particularly those from South Africa and
Brazil—are tinted when uncut, probably by reason of the action upon
them of their matrix, especially if ironstone, or with rolling for ages
amongst ironstone in river-beds, which gives them a slight metallic
appearance ; in each case the cause is suggested by the fact that these
tinted stones are usually found in such places, and that the tinting is
very thin and on the surface only, so that the cutting and shaping of
the stone gets below it to the perfectly clear diamond.
From
Pliny and other historians we gather that at various periods
considerable superstition has existed with regard to diamonds, such as
that if one is powdered it becomes poisonous to a remarkable degree ;
that gifts of diamonds between lovers—married and unmarried— produce
and seal affection ; hence the popularity of dia-
G
