D I A 
DIA'METR AL, adj. Defcribing the diameter; relat¬ 
ing to the diameter. 
DIA'METRALLY, adv. According to the direction 
of a diameter ; in direft oppofition,—Chriftian piety is, 
beyond all other things, diametrally oppofed to profane- 
nefs and impiety of actions. Hainmond. 
DIAMET'RICAL, adj. Defcribing a diameter: ob- 
ferving the direction of a diameter.—The fin of calumny 
is fet in a mod diametrical oppofition to the evangelical 
precept of loving our neighbours as ourfelves. Govern¬ 
ment of the Tongue. 
DIAMET'RICALLY, adv. In a diametrical direc¬ 
tion.—He perfuaded the king to confent to what was 
diametrically again!! his confcience and his honour, and, in 
truth, his fecurity. Clarendon. 
DI'AMINTZ, or Dunamund, a town of Rudia, in 
the government of Riga, on the coaft of the Baltic: 
twelve miles north-welt of Riga. 
DI'AMOND,yi [ diamant, Fr. adamas, Lat. of nr:ten, 
diamak, Arab, from a;iK, adorn, durable.] The mod va¬ 
luable and hardeft of all the gems.—I fee how thine eye 
would emulate the diamond: thou haft the right arched 
bent of the brow. Skakcfpeare. 
The diamond is by mighty monarchs worn. 
Fair as the ftar that ufhers in the morn. Blackmore. 
The confent of mankind, in all ages and countries, has 
fixed an immenfe value upon the diamond. The inimi¬ 
table qualities to which this preference is attached, are 
its hardnefs, which is fuch that it eafily cuts all other 
fubftances, and takes a mod exquifite and lading polifh ; 
and its very great refracting power, which is fo confide- 
rable as to occafion all the light to be refledted, which 
falls on any of its interior furfaces, at a greater angle of 
incidence than twenty-four degrees and a quarter. Hence 
its luftre, when cut into the form of a regular folid, is 
very great. This may be eafily underftood, when it is 
confidered that an artificial gem does not reflect the light 
from its hinder furface, until that furface is inclined in 
an angle of forty-one degrees. The diamond therefore 
will not only throw back all the light which an artificial 
gem would reflect, but likewife one half as much more ; 
which, falling between the angles of forty-one degrees 
and twenty-four degrees and a quarter, would have been 
fuffered to pafs through by the falfe gem. It is not fur- 
prifing, therefore, that the effect of the diamond Ihould 
be fo much greater; more efpecially when we attend to 
its Angular tranfparency, and the accuracy of its polifli. 
From its extreme hardnefs, mineralogifts have ufually 
confidered it as a ftone; yet fir Ifaac Newton long ago 
predidted, on account of its rich and peculiar effulion of 
light, that the diamond would be found eventually to 
be an inflammable fubftance. This predidtion has been 
literally fulfilled in the clofe of the eighteenth century, 
by the ingenious experiments of our countryman Mr. 
Smithfon Tennant, fince confirmed by the more elaborate 
operations of the French chemifts Guyton, Clouet, and 
Hachette. From their experiments it is clearly decided, 
that the diamond is a combuftible fubftance, confiding of 
pure carbon, or charcoal ; but from what material it de¬ 
rives its origin, yet remains to be afcertained. For par¬ 
ticulars of the above-mentioned experiments on the dia¬ 
mond, fee the article Chemistry, vol.iv. p. 387, &c. 
and for its primitive form, cryftallization, and fpecies, 
fee Mineralogy, The true diamond is perfectly co- 
lourlefs, and pellucid as the morning dew ; fo that thofe 
tinged with a colouring matter, as yellow, green, red, 
blue, brown, &c. are always inferior. Hence diamonds 
came to be diftinguifhed by the terms firjl water, which 
means the pure!! and molt pellucid ; Jecond water, or 
thofe which come the neareft in purity to the firft ; third, 
and fourth, water, &c. according to their refpedtive de¬ 
grees of purity or difcolouration. 
Diamonds are not yet certainly known to be produced 
in any other part of the world except Hindooftan, and 
Vol. V. No. 314. 
D I A 789 
the Portuguefe territory of Brazil, in South America. 
The diamonds of India are ufually found in yellow fer¬ 
ruginous earth, under rockspf quartz or fand-ft'one ; and 
fometimes in the channels of torrents, which have de¬ 
tached them from their native beds. Thofe of Brazil 
are found in a kind of pudding-ftone, impregnated with 
iron ochre. The richeft and molt celebrated diamond- 
mines are thofe of Vifiapour and Golconda ; both fitu- 
ated near ftreams that flow into the Kiftna, in the fouth- 
ern divifion of Hindooftan. Thofe mines near the city 
of Vifiapour, are in the Mahratta territory : thofe in the 
province of Golconda, are in the territory of the Nizam. 
The diamond-mine of Raolconda, about forty Britifti 
miles north-weft from the junction of the Beema and 
Kiftna, in the territory of Vifiapour, is allowed to have 
pre-eminence over all others. Next to this is the dia¬ 
mond mine of Colore, on the fouthern bank of the Kift¬ 
na, not far from Condavir. A diftrict on the river Ma- 
hanada, to the fouth of Sumboulpour, and to the north 
of the Deccan, is noted for another mine of this rich 
produdt; as is Gandicotta, on the fouthern bank of the 
river Pennar. Not far to the fouth-weft of Allahabad, 
are the diamond-mines of Penna, alfo lituated to the north 
of the Deccan, and in the province of Bundelcund, about 
fixty Britifh miles to the fouth of the Jumna, which 
flows into the Ganges. Bundelcund is a mountainous 
tradt, about a hundred miles fquare, fubjedt to its rajah. 
It is remarkable that the fineft diamonds are produced 
from thofe mines which are fituated neareft to the river 
Kiftna, which rifes at Balifur, in the chain of Sukhien. 
The diamond mines of Brazil, in the Portuguefe terri¬ 
tory of South America, are fituated near the river Mil- 
hoverde, not far from Villa Nova do Principe, in the 
province of Serro de Frio, in fouth latitude, according 
to La Cruz, 170°, longitude 44 0 W. from Greenwich. 
It is a Angular fadt,' that this invaluable fubftance is pro¬ 
duced in Hindooftan chiefly about the correfponding la¬ 
titude of 170°. But the diamonds of Brazil are not of 
fo fine a water, being of a browniflv obfcnre hue; and 
are therefore known in commerce by the name of Portu¬ 
guefe diamonds. In working the mines, the diamonds 
are found in beds of fmall veins, about an inch broad, 
that traverfe the rocks in various directions ; out oi 
which the miners draw the earth, containing thefe pre¬ 
cious gems, with fharp iron hooks. Thofe who are em¬ 
ployed are obliged to work naked, and have likewife in- 
fpedtors fet over them, to prevent theft or concealment 
of the diamonds ; but which, however, they ftill find 
means to effedt, by watching opportunities when they 
are not obferved, and fwallowing them. 
The value of diamonds, is reckoned by weight, at fo 
much the carat. The carat ufed in this valuation is di¬ 
vided into four parts, called grains ; but lefs than troy 
grains by one fifth ; for one hundred and fifty carats are 
equal to the troy ounce of four hundred and eighty 
grains. Rough diamonds, without any flaw or blemith, 
are valued at two pounds lterling the tingle carat; and 
the expence of cutting amounts to three pounds three- 
quarters the carat. The value is greatly diminiftied if 
the diamond be imperfedt, or of a bad figure; and it in- 
creafes rapidly with the iize. To find the worth of a 
rough diamond, its weight in carats muft be fquared, and 
multiplied by two, and the product will be pounds fter¬ 
ling/ A cut or finiftied diamond is worth four times as 
much as one that is rough. Thofe of the greateft bril¬ 
liancy are fometimes valued at a higher rate ; but this 
value has never been applied to (tones of exceftive mag¬ 
nitude. It does not appear that any fum exceeding one 
hundred and fifty thoufand pounds was ever given for a 
diamond; notwithstanding we are told that the great di¬ 
amond of the king of Portugal, weighing 1680 carats, is 
valued at 224 millions fterling. And alfo, that the dia¬ 
mond which adorns the fceptre of Ruflia, weighing 779 
carats, is valued at 4,854.,728 pounds fterling. This dia¬ 
mond was one of the eyes of a Malabar idol, named 
9 P Sckeringhatn, 
