GEMS. 
"sda — portraits of emperors and empreffes on the 
e ftone: we are a told what kind of topaze they 
are. Of the eee of modern arti{ts on topaze, one of the 
beft is that reprefenting the ae of Philip Il. and Den Car- 
jos, in the jul mentioned cabinet: this is a whitith topaze, 
which, as the work is that of Trezzo, has for a aig time 
been Cool tae for a diamon 
witht the pi found 
reat sates that it was en 
and. alas even oe re for the: above reafon, it 
plied for that purpofe; but this writer appears 
hy Seer ry to | coma his own ftateme nt. What we know 
or certain iS, that t fcarcely any well authenticated antique 
the aatrwe oo at Paris. e /, or agua 
arin, a varie the green emerald (fee Germ, Bery!), is 
well ae (a “Pliny, ey not ie bar met with among 
e ains ancie m of the imperial 
ent 
libr mes oe Paris poffeffes. 2 en Bd Julia, agli: of Titus, 
engraved by Evodus, on a bluifh tranfparent ftone, which is 
robably a true beryl, though it may turn to be rock- 
cryftal: it is often difficult to diftinguifh thefe two fub- 
; but whatever the one jutt- 
raving on it is, according to all 
pane a mott beavial work vof ar 
acinth is mentioned among the ftones 
whi oe mene acer employe red for engraving on, but on 
uthority ; is i 
ver 
uncertain a’ it are what the ancients un- 
derftood by their be It was certainly different from ours, 
for it is defcribed as of a violet colour, and may therefore 
: be confider ed as: mere amethyit quartz. Modern artifts have 
argon, but nothing 
of any importance is known to be ecuielt in them 
G 
arnel.— noble garnet, if we may truft the accounts 
e find of engravings ask to be in garnet, has been often 
employed bo n and ancie hes A firft rate 
a a gar n gen 
t fuch as to eee it a defir: able 
_—-has been Eaploye by the engravers of all 
times, both “for intaglios and cameos. The coloured varie- 
tiey have, in general, been preferred, efpecially the violet, 
called. amethy/f, and the brownith or blackifh, alfo known by 
amethyfle, on the erroneous 
fuppofition that rix ont the oriental amethytt ; 
which latter (being a violet ae of. the fapphire) was, for 
the reafons above Rated, not attempted. by the engravers of 
antiquity. 
OF femi-tranf{parent ftones belonging to the filiceous genus, 
feveral have been employe e prafe, one of the fub- 
ftances confounded by the ‘ancients with the merald, is a 
quartzy fubftance of the colour of leek, eee it has ob- 
tained its name. (See Prass.) Pla/ma and prafma of Italian, 
and other modern lapidaries, are corruptions o 
us idea pen en fubftance is 
rald is gen 
Chryfo aon tranflucid fle ons ae “of apple-green 
< ec CHRYSOPRASE), eae has been confounded both 
It has, cad 
mplo ae b modern engravers only 
we know, been ym 
Giopes has been hitherto found 
and, "indeed, the true 
only in Silefia. 
Opal.—The noble opal was too highly eftcemed by the 
aria as a precious {tone t que its way into the hands 
the en graver ; nor were ie mmon varieties, w ane do 
ee reflect the vivi id colours of ihe former, ufed for the pur- 
1, ON account of their foftnefs. 
mentioned as a fubitance on which the 
grave, but this is net very probable, on aes of the foft- 
nefs - the - and becaufe the ancients, if they were really 
acquainted with it, as fome writers fuppofe, muft have va- 
lued it too Nese to apply it to that purpofe. ees 
in his “ Defer iption des tofch,’ 
we 
or] 
‘ 
ower 
black, 
turns 
the es and ats a cal fhew ratum under- 
neath, which makes the white bfartpaneak layer appear as if. 
it were itfelf of a black colour. 
Calcedony and Carnelian are, with regard to their fubitance, 
very nearly. related, but they differ in colour: that of the 
ormer is generally mil sad blui hite, fometim 
proaching to fky blue ; but it isalfo found of different tints 
of yellowifh and reddifh, when into carnelian. e 
it pafles 
true calcedony is of a greyifh white-colour, and when poli 
ed and held between the eye and the light, tb caibit 
marks fimilar to the fcoopings made with a knife on wood; ; 
thefe marks are in the interior of the weenie and proceed 
ria 
rom a- 
ere are many 
es of ancient acta n calcedony extant ; for 
inftance, ve celebrated Doonifine “pull by Hyllus. The 
calcedony is generally called white carnelian by the lpidarie, 
The carnelian varies in its colour. from deep cherry,.a: 
even blood red, to reddifh white, and paiies ee one lide i into 
ark brown, and ont 
of the Nicolo. The oak: od mo of tr 
e fuperior to 
who did not over ioe thiscircum- 
flance, feed that a ‘ancients had a particular way o 
clarifying the lefs pure cx “elans, and to » give | them a brighter 
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