51 6 
ground, found a natural fragment of twenty- 
live carats. 3. That of Soumelpour, a large 
town in the kingdom of Bengal, near 
the diamond-mine. This is the most antient 
of all, and should rather he called that of 
Goual, which ;s the name of the river, in the 
sand whereof these- stones are found. Lastly, 
the fourth mine, or rather the second river, 
is that of Succudan, in the island of Borneo. 
I he diamond, we have already observed, 
is thui hardest of ail precious stones. It can 
only be cut and ground by itself and its own 
substance, do bring it to that perfection 
which augments its price so considerably, 
they begin by rubbing -several against each 
other while rough, alter having 'first glued 
them to the ends of two wooden blocks, thick 
enough to be held in the hand. It is this 
powder thus rubbed off the stones, and re- 
ceived in a little box for the purpose, that 
serves to grind and polish the stones. Dia- 
monds are cut and polished by means of a 
mill, which turns a wheel of soft iron sprinkled 
oyer with diamond-dust mixed with oil of 
olives. The same dust well ground and di- 
luted with water and vinegar, is used in the 
sawing of diamonds ; w hich is performed with 
an iron or brass wire, as line as a hair. Some- 
times, in lieu of sawing the 'diamonds, they 
cleave them, especially if there are any large 
shivers in them. But the Europeans are not 
usually daring or expert enough to run the 
risk of cleaving, for fear of breaking. 
The first water in diamonds, means the 
greatest purity and perfection of their com- 
plexion, which ought to be that of the purest 
water. When diamonds fall short of this 
perfection, they are said to be of the second 
or third water, &c. till the stone may be pro- 
perly called a coloured one : for it would be 
an impropriety to speak of an imperfectly co- 
loured diamond, or one that has other de- 
lects, as a stone of a bad water only. 
Mr. Boyle has observed, from a person 
much conversant in diamonds, that some of 
these gems, in their rough state, were much 
heavier than others of the same size, espe- 
cially if they were cloudy or foul. With 
regard to their specific gravities, Mr. Ellicot, 
who made many experiments, has drawm'out 
a table of their several differences with great 
care and accuracy. This, taking in all the 
common varieties in diamonds, may indeed 
serve as a general rule for their mean gravity 
and differences. From this the mean specific 
gravity of the Brasil diamonds appears to be 
3513; of East India diamonds, 3519; the 
mean of both, 3517. Therefore, if any thing 
is to be concluded as to the specific gravity 
of the diamond, it is, that it is to water as 
3517 to 1000. 
For the valuation of diamonds of all weights 
Mr. Jefferies lays down the following rule. 
He first supposes the value of a rough dia- 
mond to be settled at 2/. per carat at a me- 
dium; thenio find the value of diamonds of 
greater weights, multiply the square of their 
weight by 2, and the product is the value re- 
quired : e. g. To find the value of a rough 
diamond of two carats : 2 x 2 = 4, the 
square of the weight; which, multiplied by 2, 
gives 8/. the true value of a rough diamond 
of two carats. For finding the value of ma- 
nufactured diamonds, he supposes half their 
weight to be lost in manufacturing them; 
and therefore, to find their value, we must 
multiply the square of double their weight by 
DIAMOND. 
2, which will give their true value in pounds. 
Thus, to find the value of a wrought diamond 
weighing two carats ; we first find the square 
of double the weight, viz. 4 x 4 = 16 ; then 
10 x 2 = 32. So that the true value of a 
wrought diamond of two carats is 32/. On 
these principles Mr. Jefferies has constructed 
tables of the price of diamonds from 1 to 1 00 
carats. 
The largest diamond ever known in the 
world is one belonging to the king of Portu- 
gal, which was found in Brasil. It is still un- 
cut: and Mr. Magellan informs us, that it 
was of a larger size ; but a piece was cleaved 
or broken off by the ignorant countryman 
who chanced to find this great gem, and tried 
its hardness by the stroke of a large hammer 
upon the anvil. This prodigiQus diamond 
weighs 1680 carats; and though uncut, Mr. 
Rome de l’lsle says that it is valued at 224 
millions sterling ; which gives the estimation 
of 79,36 or about 80 pounds sterling for each 
carat, viz. for the multiplicand of the square 
of its v’hole weight. The famous diamond 
in the sceptre of the emperor of Russia, 
weighs 779 carats, and is worth at least 
4,854,728 pounds sterling, although it hard- 
ly cost 135,417 guineas. This diamond ori- 
ginally was one of the eyes of a Malabarian 
idol named Scheringham; and a French gre- 
nadier, who had deserted from the Indian 
service, contrived to become one of the 
priests of that idol, and by that means to 
steal it. After passing through several hands, 
the late prince Orloff purchased it at Am- 
sterdam in 1766, for his sovereign the em- 
press of Russia. The diamond of the great 
Mogul is cut in rose, weighs 279-Jg. carats, 
and is worth 380,000 guineas, though it has 
a small flaw near the bottom ; and Tavernier, 
who fully examined it, valued the carat at 
150 French livres. Another diamond be- 
longing to the king of Portugal weighs 215 
carats, is extremely fine, and is worth at least 
369,800 guineas. The diamond of the em- 
peror of Germany weighs 1 394 carats, and is 
worth at least 109,520 guineas. It is said 
this diamond has a little hue of a citron co- 
lour. The diamond once the property of the 
late unfortunate king of France, called the 
Pitt or Regent, weighs 136| carats: this gem 
is worth at least 208,333 guineas, although it 
did not cost above half that sum. Another 
diamond of the same monarch, called the 
Sana/, weighs 55 carats, cost 25,000 guineas, 
and is said to be worth much more. 
Diamond, brilliant, is that which is cut 
in faces both at top and bottom ; and whose 
table, or principal face at top, is flat. To 
make a complete square brilliant, if the rough 
diamond is not found of a square figure, it 
must be made so ; and if the work is perfect- 
ly executed, the length of the axis will be 
equal to the side of the square base of the py- 
ramid. Jewellers then form the table and 
collet by dividing the block or length of the 
axis into 18 parts. To render a brilliant per- 
fect, each corner of the table-diamond must 
be shortened by l-20th of its original. The 
corner ribs of the upper sides must be flatten- 
ed or run towards the centre of the table 
l-6t.h less than the sides ; the lower part, 
which terminates in the girdle, must be I -8th 
of one side of the girdle ; and each corner 
rib of the under side must be flattened at the 
top to answ er the above flattening at the gir- 
dle, and at bottom must be l-4thofeach side 
■Q 1 
of the eol'et. The parts of the small work 
which completes the brilliant or the star ancl 
skill facets, are of a triangular ligure. Both 
of these partake equally of the depth of the 
upper sides from the table to the curdle, and 
meet in the middle of each side of the table 
and girdle, as also at the corners. Thus thev 
produce regular lozenges on the four upper 
sides and corners of the stone. The trian- 
gular facets, on the under sides, joining to 
the girdle, must be half as deep again ay the 
above facets, to answer to the collet part. 
The stone here described is said to be a Lull- 
substanced brilliant. If the stone is thicker 
than in the proportion here mentioned, it is 
said to be an over-weighted brilliant. If the 
thickness is less than in this proportion, it is 
called a spread brilliant. The beauty of bril- 
liants is diminished from their being either 
over-weighted or spread. The true propor- 
tion of the axis or depth of the stone to its 
side is as 2 to 3. Brilliants are distinguished 
into square, round, oval, and drops, from the 
figure of their respective girdles. 
Diamond, Cornish, a name given by 
many people to the crystals found in digging 
the mines of tin in Cornwall. These cry- 
stals are of the nature of the Kerry-stone of 
Ireland, but somewhat inferior to it. They 
are usually bright and clear, except towards- 
the root, where they are coarse and foul, or 
whitish. They are usually found in the com- 
mon form of an hexungular column, termi- 
nated at each end by an liexangular pyramid- 
Diamond, rose, is one that is quite flat 
underneath, with its upper part cut in many 
little faces, usually triangles, the uppermost of 
which terminate in a point. In rose-diamonds 
the depth of the stone from the base to the 
point must be half the breadth of the diameter 
of the base of the stone. The diameter of the 
crown must be two-thirds of the diameter of 
the base. The perpendicular, from the base 
to the crown, must be three-fifths of the dia- 
meter of the stone. The lozenges which ap- 
pear in all circular rose-diamonds, will be 
equally divided by the ribs that form the 
crown; and the upper angles or facets will 
terminate in the extreme point of the stone* 
and the lower in the base or girdle. 
Diamond, rough, is the stone as nature 
produces it from the mine. It should be 
chosen uniform, of a good shape, transpa- 
rent, not quite white, and free from flaws and 
shivers. Black, rugged, dirty, flawy, veiny 
stones, and all such as are not tit for cutting, 
are pounded in a steel mortar made for that 
purpose; and when pulverised, the dust 
serves to saw, cut, and polish the rest. Shivers- 
are occasioned by the miners attempting to 
get them more easily out of the vein, which 
winds between two rocks, by breaking the 
rocks with huge iron levers, which shake, 
and thus till the stone with cracks and shivers. 
The antients had two mistaken motions with 
regard to the diamond: the first, that it be- 
came soft by steeping it in hot goat’s blood ; 
and the second, that it is malleable, and bears 
the hammer. 
Diamonds and precious stones may be im- 
ported duty-free, saving the duty granted to 
the East India company on diamonds import- 
ed from any place within the limits of their 
•charter. 6 Geo. II. c. 7. s. 1. 2. 
Diamond, in the glass trade, an instrument 
used for squaring the large plates or pieces ; 
and, among glaziers, for cutting their glass. 
