|
64
|
NATURAL HISTORY OF GEMS.
|
||
|
|
|||
|
fourth
sort, the Sermani, " having spots of gold," can be no other than a
shade of the Lapis-lazuli. As to the natural properties of the
Turquois, he avers "that it grows clear or dull according to the state
of the weather, and on rainy days has a greater circumference than on
fine. One species gains a better colour by maceration in oil, but'loses
it again after a time. According to the age since it has been dug, the
Turquois is divided into that of the Old,* and of the New mine
: the latter does not keep its colour." This distinction is still in
force ; Turquois " de la vieille roche," however, actually means at
present nothing more than one of the best quality, and supposed not
to be liable to fade. Nishapur continues to furnish the only Turquois
of commercial value : they are brought stuck upon rolls of wax by
Tartar and Persian merchants to the great fair of Nishni-Novogorod.
Lately, some have been brought direct to this country from the foot of
Mount Sinai, where they occur in strata of a sandstone rock. This new
find is of a remarkably rich azure, superior when recent to the finest
Persian, but (a fatal drawback) liable to change yet more rapidly and
capriciously than any of the old. j The above-quoted
*
This " Old Mine or Rock," says Chardin, " was in a mountain, Firuz-cos,
distant three days' journey from the Caspian. All its produce was
reserved exclusively for the Shah; whatever found its way into the
market was due to the embezzlement of the miners and their directors ;
a source of supply by no means scanty. No wonder, therefore, that when
Chardin was allowed to visit the Treasury at Ispahan he beheld in each
chamber the stones in the rough, piled high on the floor like heaps of
grain, and the polished filling innumerable leather bags, weighing 45
to 50 lbs. each."
t
The unfortunate liability of so costly a stone to lose its colour and
therewith its value, exercised the ingenuity of the lapidaries of De
Boot's age in devising methods for restoring it. Some, distilled
ultramarine in aqua-regia, and polished the spoilt Turquois with the
residuum, others, after macerating the gem in aqua-regia, and washing
it in vinegar, threw it into ice-cold water. A third and more approved
method was to eat away the surface with oil of vitriol ; but of all the
recipes (the
|
|||
|
|
|||