and scarcely to be described grating sound, which is one of their most
remarkable characteristics. By this alone rough diamonds may be
accurately and expeditiously distinguished from every other gem.
It is usual to cut diamonds into three principal forms, called
_brilliant_ (Pl. II, Fig. 7), _rose_ (Fig. 8), and _table_ diamonds
(Fig. 9). Brilliants are, for the most part, cut from such of the stones
as have naturally a crystallized shape, and rose diamonds from the flat
varieties. The former are so called from their great lustre, in
consequence of the facets on both sides being cut. These are always set
upon a black ground, whilst rose diamonds, which are much thinner, are
set upon a white foil speckled with black, for the purpose of adding to
their lustre. Rose─cut diamonds are of course much less estimable than
brilliants; so much so indeed, that of late many of them, brought from
Holland, have been re─cut into brilliants, notwithstanding the
additional expense, and the loss of size necessarily attendant on this
operation. The table diamond is the least beautiful of any. This mode of
cutting is only adopted for such stones, or rather fragments, as, with a
considerable breadth, have only a very trifling depth. The
diamond─cutters of England are considered to be the best in Europe, but
their number is so small as to occasion many stones to be sent to
Holland to be cut.
The value of diamonds is ascertained by their weight in carats; and this
value increases, in a very high ratio, according to their magnitude. For
instance, a diamond weighing one carat will be worth about 10_l._ whilst
another of five carats will be worth 150_l._ and of ten carats
800_l._[2] This rule, however, can only be taken for diamonds of twenty
carats and under. The larger ones, in consequence of the scarcity of
purchasers, are generally disposed of at prices greatly inferior to
their estimated worth. The value of some diamonds that are peculiarly
perfect exceeds the above ratio; whilst, for a stone that is cloudy,
foul, or of bad colour, even three quarters of the estimated value will
perhaps be deducted.
Footnote 2:
A Carat is equal to four jeweller’s grains, seven grains of which are
equal to six grains troy. To ascertain the value of wrought diamonds
the weight must be doubled, about half being supposed to be lost in
the working. This sum must be multiplied into itself, and the product
by two. Thus to find the value of a diamond of twenty carats 20 × 2 =
40 × 40 = 1600 × 2 = 3,200_l._
No diamonds are so valuable as those that are perfectly transparent, and
of snow─white colour. The green and yellow varieties are, however, much
esteemed: the blue kinds were formerly more valued than at present; and
the least valuable are those that have a grey or brownish tint. Black
diamonds are much prized by collectors.
The principal use of the diamond is in jewellery. It is also used by
lapidaries, for slitting hard stones, and for cutting and engraving upon
other gems; by clock─makers in the finer kinds of clock─work; in the
glass─trade for squaring large pieces or plates of glass, and among
glaziers for cutting their glass.
The largest diamond ever known (if it be such, and not a white topaz, as
some people have imagined) is in the possession of the Queen of
Portugal, and weighs 1,680 carats, or more than _eleven ounces_. It was
found in Brazil, and sent to Lisbon in the year 1746. It is still uncut,
and has been valued at 5,644,800_l._
The Rajah of Mattan, in the island of Borneo, possesses a large diamond,
shaped like an egg, with an indented hollow near the smaller end. It was
found in that island about eighty years ago, is said to be of the finest
water, and to weigh 367 carats, or more than two ounces and a quarter.
Several years ago the Governor of Batavia, desirous of purchasing this
gem, sent a Mr. Stuvart to the Rajah, authorizing him to offer for it
150,000 dollars, two large brigs of war, with their guns and ammunition,
together with a certain number of great guns, and a quantity of powder
and shot. The Rajah, however, refused to deprive his family of so
valuable an hereditary possession; for the Malays not only attach to it
the miraculous power of curing all diseases by means of water in which
it is dipped, but also believe that the fortune of the family is
sustained by its continuing in their possession.
Tavernier, the French Traveller, saw in the possession of the Great
Mogul a diamond which weighed near 280 carats. In form and size it
resembled half a hen’s egg. This diamond had been obtained from the mine
of Coulour, about the year 1550; and was valued at more than 700,000_l._
sterling.
The sceptre of the Emperor of Russia is adorned with an oriental diamond
about the size of a pigeon’s egg, which weighs 195 carats. This diamond
is said to have once been placed as the eye of an idol in Seringham, in
the Carnatic. A grenadier, who had deserted from the French service in
India, contrived to become one of the priests of the idol, in the hope
of being able to steal this eye. He at length effected his purpose, and
escaped with the diamond to Madras, where he sold it to the captain of a
ship for a sum equal to 2,500_l._ of British money. It was afterwards
transferred to a Jew for 18,000_l._ Coming into the hands of a Greek
merchant, he offered it for sale at Amsterdam, in 1766; and the Russian
Prince Orloff bought it for the Empress Catharine for about 90,000_l._
sterling, and an annuity of 4,000_l._ during the life of the person who
sold it.
The _Pitt_, or _Regent diamond_ (Pl. II, Fig. 10), which lately was set
in the handle of the sword of state of Buonaparte, and is now possessed
by the king of France, is a brilliant of the most beautiful kind, and
weighs 136¾ carats. It was brought from India by Thomas Pitt, Esq.
Governor of Fort George. Mr. Pitt has himself stated, respecting it,
that, in December, 1701, whilst resident in Madras, several valuable
stones, in a rough state, were brought to him for sale by an eminent
diamond merchant. One of these, the diamond here spoken of, was so large
that the merchant asked for it the sum of 85,000_l._ After much
bargaining, Mr. Pitt purchased it for 20,400_l._ He afterwards sold it
for 135,000_l._ to the Regent Duke of Orleans; and by him it was placed
among the crown jewels of France.
The _Pigot diamond_ weighs forty─seven and a half carats. This, which is
an extremely fine stone, was disposed of by lottery, in 1800, for
22,000_l._; and is now in the possession of Messrs. Rundell and Bridge,
jewellers in London.
A large star, cross, and chain, worn on grand gala days by the Prince of
Brazil, as Sovereign of the different Portuguese orders of knighthood,
are each ornamented with a great number of magnificent diamonds, set in
gold. The centre diamond of the star is alone valued at 800,000_l._
When the diamond is rubbed it will attract bits of straw, feathers,
hairs, and other small objects; and if exposed to the rays of the sun,
and immediately taken into a dark place, some diamonds will appear
luminous.
ZIRCON FAMILY.
51. _JARGOON is a gem usually of smoky yellow or brownish colour, and
sometimes limpid: if placed upon any object, it exhibits of it a very
distinct double image._
_The primitive form of its crystal is an octohedron (Pl. II, Fig. 5),
but it is frequently crystallized in right─angled prisms, terminated by
four─sided pyramids._
In hardness this stone does not much exceed that of the emerald. The
greyish white and yellowish white varieties of jargoon are valuable
chiefly on account of their resemblance to the diamond. The
darker─coloured varieties can be deprived of their colour by heat; and,
in this state, though in lustre they are infinitely inferior to them,
they are sometimes substituted for diamonds. Jargoons are now seldom
used except for the jewelling of watches and time─pieces. About a
century ago, they were much used in mourning ornaments, for which the
dark tone of their colour, and their almost adamantine lustre, were
supposed to be peculiarly appropriate.
The jargoon is principally brought from the island of Ceylon; but it is
occasionally found in France, and Spain, and in granite rocks near
Cuffel, in Dumfrieshire, Scotland.
52. _The_ HYACINTH, _or_ JACINTH, _is a dark orange─red variety of
jargoon_. It is also chiefly imported from Ceylon, where it is generally
found in the sand of rivers, in irregularly round pieces, but seldom of
large size without flaws.
This stone is indebted for its name to a supposed resemblance in colour
to that flower, which, according to the Pagan mythology, Apollo raised
from the blood of his favourite youth, Hyacinthus.
When bright, and free from flaws, the hyacinth is a superb ring stone;
but it is not of usual occurrence in modern jewellery.
RUBY FAMILY.
53. _The ORIENTAL SAPPHIRE is a gem of blue colour, the shades of which
vary from a full and deep tint to a nearly colourless appearance, and
sometimes it is party─coloured._
_It is found crystallized in six─sided pyramids much lengthened and
joined base to base (Pl. II, Fig. 13); and also in rounded or
pebble─shaped fragments. It has a foliated texture, is extremely hard,
and about four times as heavy as water._
We are chiefly indebted for the sapphire to the East Indies and the
Island of Ceylon, where it is found amongst the sand of the rivers. When
brought into Europe, it is cut by means of diamond powder, and polished
with emery. It is now usually set with a foil of its own colour; but it
was formerly the practice, instead of foil, to place under this stone
the blue part of a peacock’s feather.
In hardness the sapphire ranks next to the ruby (54); and in value it is
about equal to the emerald (67). A good sapphire of ten carats’ weight
is worth about fifty guineas. In the Museum of Natural History at Paris
there is a sapphire which weighs upwards of sixty─six carats: it was
placed there from the wardrobe of the crown.
We are informed by M. Hauy that sapphires are found in Bohemia and
France, particularly in one part of the Ville du Puy, among the sand of
a rivulet near Expailly. In the summer─time, when the rivulet is nearly
dry, they are collected by persons, each of whom is furnished with a
small tray and a linen bag. Where─ever there are small depressions in
which the water has been stationary, these persons enter them, and fill
their trays with the sand. This they wash in water in such manner that
the lighter particles are carried away; whilst the heavier ones of
gravel, sapphire, and other articles, remain at the bottom.
Some sapphires exhibit a kind of opalescence, or whitish floating light
in their interior. Sapphires lose all their colour in the fire; and,
after having been subjected to heat, they are so hard and transparent as
sometimes to be sold for diamonds.
54. _ORIENTAL RUBY is a precious stone of intense and bright red colour,
occasionally varied with blue, and sometimes party─coloured._
_In the general form of its crystals it much resembles the sapphire
(53)._
The ruby is imported into this country from the East Indies, though
seldom in a rough state, as the stones are almost always first cut by
the Indians for the purpose of ascertaining their value. They are said
to be found in the sand of certain streams near the town of Sirian, the
capital of Pegu; and with sapphires in the sand of rivers in Ceylon. But
they are so seldom seen of large size, that a ruby above thirty─one
carats’ weight, of perfect colour, and without flaws, is even more
estimable than a diamond of equal weight. The ruby is usually set with a
foil; but, if peculiarly fine, it is sometimes set without bottom, that
the stone may be seen through.
Tavernier, the Eastern traveller, states that, in the throne of the
Great Mogul, he saw 108 rubies, which, on an average, weighed from 100
to 200 carats each. Among the jewels of the King of Candy, that were
sold by auction in London, on the 13th of June, 1820, was a ruby which
measured two inches in length, and one inch in breadth. It was, however,
interesting only as a specimen for a cabinet, for it had, in various
directions, a great number of small hair─like tubes running through it.
The hardness of this stone is such that the ancients do not appear to
have possessed the art of cutting it; and, in the improvements which of
late have been made by Mr. Earnshaw in the construction of time─keepers,
no stones have been found sufficiently hard for jewelling the holes,
except the ruby and the diamond.
There are several modes of counterfeiting rubies; and some persons have
succeeded so well in imitating these stones, that even the most able
lapidaries, till they try the hardness, may be deceived.
55. _The ORIENTAL AMETHYST is an extremely rare gem, usually of purple
colour, apparently formed by an union of the colouring matter of the
sapphire and the ruby_. This stone, if heated, loses its colour, and
becomes transparent. After this process its brilliancy is such that it
is scarcely distinguishable from the diamond; and, in jeweller’s work,
it is occasionally substituted for that gem. The common amethyst (79),
or that which is chiefly seen, is nothing more than a violet─coloured
rock crystal (78).
56. _The ORIENTAL TOPAZ and EMERALD are each varieties of the oriental
ruby, the former straw─coloured and the latter green_. This kind of
emerald is imported from Pegu, and some other parts of the East Indies,
and is an extremely rare gem.
57. _The SPINEL and BALAIS RUBY are two kinds of precious stones, which
differ from each other principally in colour, the former being of a
carmine, and the latter a cochineal red._
_They vary from the oriental ruby (54) in being less hard; in the
primitive form of their crystals being regular octohedrons (Pl. II, Fig.
5), and in their not being much more than 3 times heavier than water._
Although these two kinds of rubies are inferior, both in lustre and
colour, to the oriental ruby; yet, when they exceed a certain size, they
are much esteemed. A spinel that weighs more than four carats is valued
at half as much as a diamond of the same weight, and is not unfrequently
imposed upon ignorant purchasers for the oriental species. It is easily
wrought, takes a high polish, and is certainly a beautiful gem. Being
too expensive for necklaces, it is usually set in rings and brooches,
surrounded by brilliants.
The spinel ruby is found amongst sand, in one of the rivers of Ceylon,
which flows from the high mountains, towards the middle of the island.
It is also found in Brazil; and in Hungary, Bohemia, and Silesia.
The Balais ruby is so named from Balacchan, the Indian appellation of
Pegu, from which country it is chiefly imported.
58. _EMERY is a very hard opaque mineral, of blackish or bluish grey
colour, which is chiefly found in shapeless masses, and mixed with other
minerals. It is about four times as heavy as water._
The best emery is brought from the Levant, and chiefly from Naxos, and
other islands of the Grecian Archipelago, where it occurs abundantly, in
large, loose masses, at the foot of primitive mountains. It is also
found in some parts of Spain; and is obtained from a few of the iron
mines in our own country.
In hardness it is nearly equal to adamantine spar; and this property has
rendered it an object of great request in various arts. It is employed
by lapidaries in the cutting and polishing of precious stones; by
opticians, in smoothing the surface of the finer kinds of glass,
preparatory to their being polished; by cutlers, and other manufacturers
of iron and steel instruments; by masons, in the polishing of marble:
and, in their respective businesses, by locksmiths, glaziers, and
numerous other artisans.
For all these purposes it is pulverized in large iron mortars, or in
steel mills; and is afterwards separated, according to the several
degrees of fineness that are required, by washing it in water, and
suffering the grosser particles to deposit themselves. By this operation
the finer particles, which remain suspended in the water, and which are
obtained by decanting the water off, and suffering it to stand for a
considerable time, are separated. The particles first deposited are
again ground, and again agitated in the water, to separate the finest.
By these successive operations the emery is reduced to a powder so fine
that, when rubbed between the fingers, it communicates no sensation
whatever of grittiness. In general those particles only of the emery
which remain suspended in the water, after it has stood about half an
hour, are used to polish metals.
59. _ADAMANTINE SPAR, or IMPERFECT CORUNDUM, is a very hard and nearly
opaque stone, which varies much in colour, but is chiefly grey, with a
greenish, brown, or bluish tint._
_It is usually found in the form of six─sided prisms, but it sometimes
occurs in shapeless masses, has a foliated texture, and is about four
times as heavy as water._
The name of adamantine spar was given, by the British lapidaries, to
this substance from its hardness being nearly equal to that of the
diamond. It was originally discovered among the granite rocks of China;
but it has since been found, and in greater purity, in Bengal and
Ceylon.
In a powdered state this substance has long been used by the artists of
India and China for the cutting and polishing of precious stones, and
even of the diamond; but, though it will in some degree operate upon
that gem, it is not sufficiently hard to bring out the peculiar beauty
of it in a degree at all comparable to that which is effected by the
European lapidaries with diamond powder. The Chinese also use adamantine
spar for polishing steel, and in the composition of the finer kinds of
porcelain or earthenware. For the cutting of seals and precious stones
European workmen consider it preferable to emery; but, for minute
engraving, it is much inferior to diamond powder.
60. _CHRYSOBERYL is a gem of yellowish or brownish green colour, harder
than quartz (76), and sometimes transparent; but often only
semi─transparent, in which case it exhibits a bluish light, floating in
the interior of the stone._
_It is usually found in rounded pieces, but is sometimes crystallized in
compressed six─sided prisms, and in double six─sided pyramids._
So little is this gem in request in Europe, that it is seldom to be
found in the possession of jewellers; but in Brazil it is considered
inferior only to the diamond. It is usually procured from South America;
yet it occurs in Saxony; and, with the ruby and sapphire, amongst sand
in the rivers of Ceylon.
Such is the hardness of the chrysoberyl, that, when properly polished,
which is a difficult operation, it is capable of receiving a lustre
nearly equal to that of the diamond. We are informed that, a few years
ago, a considerable number of these gems were imported into this country
from Brazil, but that the greater part of them were entirely spoiled by
inferior workmen, and that the rest were so ill─cut that they remained
unnoticed, and without value. The smaller stones are said to appear to
most advantage in circular ear─drops; and the larger specimens form
necklaces and ring stones of great beauty.
The variety which exhibits an opalescent appearance, or presents a
bluish light, undulating as it were in the interior of the stone, and
changing its situation according to the position of the observer, is
chiefly valuable as an article of curiosity: the transparent kind is
always preferred by the jeweller.
SCHORL FAMILY.
61. _The TOPAZ is a gem usually of a wine─yellow colour, but sometimes
orange, pink, blue, and even colourless, like rock_ _crystal; of a
lamellar or foliated structure, harder than quartz, but not so hard as
ruby._
_It varies considerably in its crystallization; is 3½ times heavier than
water; and, when placed upon any object, shows a double image of it._
The name of topaz is derived from an island in the Red Sea, where the
ancients found a stone, but very different from ours, which they
denominated topaz. The best topazes are of a deep colour, and are
imported from Brazil; the most brilliant ones are supposed to be those
of Saxony; but the latter are generally of very pale colour. This
species of gem is found in many parts of Europe, but defective in
transparency, and sometimes even opaque. It occurs in large crystals,
and rolled masses, in an alluvial soil (269), in the upper parts of
Aberdeenshire, Scotland; and in veins, along with tin─stone, at St.
Anne’s, in Cornwall. Topazes, more than a pound in weight, have been
found in Scotland.
Mr. Mawe speaks of a topaz mine at Capon, near Villa Rica, in Brazil. In
two breaks or slips of the rocks, he says, there were little soft places
where the negroes found the topazes by scraping in them with pieces of
iron. He himself observed at least a cart─load of inferior topazes, any
number of which he might have taken away; but all that he saw were
defective and full of flaws.
These stones vary much in size; some, particularly those of Siberia,
being extremely small, and others being upwards of an inch in thickness.
In the Collection of Natural History at Paris there is a Brazilian topaz
which weighs four ounces and a quarter. These stones are not
sufficiently scarce to be, in general, much valued by the jeweller or
lapidary. The deep yellow variety is preferred to the pale sort,
although the latter is often superior to it both in size and hardness.
Figures have sometimes been engraved on the topaz; and these, when well
executed, are of great value. In the National Museum at Paris there is a
superb Indian Bacchus engraven on a topaz. The cabinet of the Emperor of
Russia contains several fine topazes of this description.
Some of the coarse kinds of topaz are broken down, pounded, and used
instead of emery for the cutting of hard minerals; and powdered topaz
was formerly kept in apothecaries’ shops, and sold as an antidote
against madness.
It is a somewhat singular circumstance, that, if the Saxon topaz be
gradually exposed to a strong heat in a crucible, it will become white
and, on the contrary, that Brazilian topazes by the same process become
red or pink. By exposure to a still stronger heat, the Brazilian topaz
changes its colour to a violet─blue.
Jewellers usually divide topazes into the following kinds:
62. BRAZILIAN and SAXON, already mentioned.
63. BOHEMIAN.—These are found chiefly in the tin mines of Bohemia, are
of small size, deficient in transparency, have only grey or muddy white
colours, and are of little value.
64. BLUE TOPAZ.—This is a large Brazilian gem, which varies in size from
one or two carats to two or three ounces. A fine blue topaz, without
flaw, and which weighed an ounce and a quarter, was sold for 200
guineas. It is sometimes difficult to distinguish a blue topaz from an
aqua marine (68).
65. PINK TOPAZ.—Some beautiful rose─coloured varieties of topaz have
been brought from Asia Minor, and others are found in South America; but
the pink topazes in the jewellers’ shops are chiefly stones of the
yellow Brazilian kind, which have had their colour changed by heat.
66. The WHITE, or NOVA MINA TOPAZ, is a perfectly colourless and
transparent variety. It generally occurs of small size, and is in
considerable estimation in Brazil for ear─rings, or for being set round
yellow topazes. Small stones of this description have recently been
found at St. Michael’s Mount, in Cornwall.
There is imported from Brazil a yellow kind of crystal (83), which is so
similar, in its appearance, to the yellow topaz as sometimes to be
imposed upon purchasers for that stone.
67. _The EMERALD is a well─known gem, of pure green colour, and somewhat
harder than quartz._
_Its natural form is a short six─sided prism; but it is sometimes found
massive, and rounded like a pebble._