76 
THE TROPICAL 
AQR!CULTUR]S"r. 
[July i, 1891. 
PROFESSOE MIDDLBTON ON ANCIENT 
GEMS.* 
"Gems," ia common speech, means a precious 
stone, especially when engraved for an ornament 
or other purpose. This, putting aside its primary 
meaning of a " bud," is prttty Learly its significance 
in clas-ical Latin, though in both languages it 
might be loosely extended to comprise a pearl. 
As used by Professor Middleton in this admirable 
manual, it bus of necessity a somewhat wider 
signiiioanoe, taking in certain materials other than 
the many varieties of precious stones. It iucludes 
for instance, Egyptian scarabs, which are often 
made out of clay or steatite (a variety of talc), 
Hittite " gems," for which limestone and marble, 
among other inateriais, were used, PLoenician 
scarabs, and the metal signets found m the MyceL» 
tombs. These are curious and interesting, and 
some exhibit deliouta workmanship an^i, oocasionally, 
great artistic skill. Sail, the most attractive part 
of Professor Middleton's subject is that which is 
concerned with the gem proper, and that as it 
was handled by Greek or Roman artists. Precious 
stones have always been the most fascinating of 
human possessions. Their intrinsic beauty, goes 
for something ; their durability for more. The 
imagination is fired when we know that the article 
one toucihes is exactly the same as it presented 
itself to human ejes and bands thousands of years 
ago; and the feeling is intensified when art has 
added to the precious material, in the design, the 
name oi the owner, or it may be of the engraver, 
a distinct human interest. 
When we talk of pieoicus stones, however, it 
must be remembered that the minerals of which 
the vast majority of the finest antique engraved 
gems are made are by no means rare or costly. 
The diitmoad, for instance, though it occurs in 
ancient art, occurs only in its natural crystal, the 
art of working it not having bten discovered till 
comparatively recent times. (The "diamond" of 
the High Priest's breast-plate was possibly a white 
sapphire. The miaerals used oeloug in the main 
to a single species knawn ao quartz, and consisting 
of silic i, the oxide of a non-metallic element ca led 
silicon. Of these silicious stones there are numberless 
varieties, differing frem one another in texture and 
colour, and through the presence in small quantities 
of accessory or intruding materials. Colourless 
rock crystal is the fundamental type of the species. 
Amethyst differs from it only in its colour, which 
ia generally violet, but sometimes citrine, and it.s 
curious parquttied structure. Among the translu- 
cent varieties of quartz are the sard, o£ which 
Professor Middleton remarks thit "it is the most 
beautiful material commenly used for ancient en- 
graved gems," a stone umber-coloured, red, or 
joddish-brown ; the loss translucent corm lian 
(Professor Middleton, always calls it carrielian, 
erroneously, we cannot but thiuk), chalcedony, 
which IS milky or bluish, the apple-green chryso- 
prase, and the leaf-green plasma. Jasper, of which 
there are many varieties, and which is of very 
common occurrence, is almo»t ops^que. Another 
very common stone is the onyx, which is mado 
up_of two or more bands of strata, varying in 
translucency and hue; when one ot these stratus 
coiiDiSiw oi sard, it is callei a sardonyx. That 
sardonyx is peculiarly interesting from its frequent 
mention in claspioiil writers. Plato speaks of i , 
thoUfih, as Professor Middleton tells us, it does 
not often occur in Greek gems. Tho Pwomaiis 
used it largely, following the fashion set by 
^he elder Kcipio AfricH nus. Amon)' nr n Hilicionsi 
*TUe Ear/ raved (Jcriis of Cla.snical Timcti. iij .J. ii iii--> 
Middleton, Camtiridjje: The Uuiversity Pi-esa-ldQl. 
stones are the chrysoberyl, the topaz, the emerald, 
the almandine and other garnets, the peridot, 
the turquoise, the opal, and the lapis iazuli (the 
sappvrus of Pliny the elder), — and these, from 
tho peridot onwards, are softer than quartz, or 
even than ancient paste or glass. It must be 
remembered that, for artistic purposes, the most 
transparent substances, whatever their intrinsic 
charms, are not necessarily the most beautiful. 
It is the translucent stones, such as sard and 
chalcedony, that are more suitable. Through these, 
light, but not the forms of objects, can be discerned, 
and so they rev^al the charms of fine and noble 
workmanship more than do the perfectly clear 
beryl and rock-crystal. In the former, the light 
pisses less regularly — that is, with more ecatiering 
of the rays — than is the case with transparent 
stones, and thus the design seems to be illuminated 
from within. On the other hand, tbe opaque 
substances are less suitable for the purpose. Even 
such stones as the heliotrope and the turquoise, 
which are capable, when in thin splioiers, of 
transmitting a little lit^ht, produce an eficot other 
and more pleasing than do the perfectly opaque 
materials. Hume of the incident light plunges a 
little way below the surface of the gem, and hghts 
up its superficial layer. 
Precious st mes, like all other things of value, 
have been imitated. So we find that many "gems," 
as it will be still convenient to call them, have 
been wrought or reproduced in paste and glass. 
Paste was a hard glass coloured by various 
metallic oxides, such as those of manganese, 
iron, coijper, and cobalt. Sometimes a pitsce I'f 
paste was titated by the gem-engraver just as if 
it were a natural stone, and sculptured by the 
aid of the same tools ; but more generally the 
glass was melted and pressed into a mould. Such 
a moul 1 had been taken from an engraved gem 
by a pellet of clay which was afterwards h^irdened 
by fire. Paste-gems are often of great beauty ib 
colour and design, though tje material lacks some 
thing of tbe optical properties which distinguish 
not a few of the true natural stoned. 
The tools and processes employed in ancient 
times in engraving gems are virtually the same 
as those in use today. The tools were five in 
number. The drill worked by a bow was the 
chief. It varied in size, was made of bronze, and 
acted in virtue of the emery or corundum powder 
(mixed with oil) with which its point was smeared. 
The drill was occasionally tubular; in that case 
its crowu was sometimes s-st with small crystals 
of corundum. The second tool was a wire- 
saw, made effective with the same abrading material. 
The wheel, or disc of broiize, was similarly employed. 
A file was also used, not of meial, but of a mix- 
ture of emery and resin, heat d together, and 
than allowed to solidify by cooling. The fifth tool 
was a graver, made by mounting in an iron or 
bronze handle a crystal or crystalline fragment of 
diamond or of sapphire, or sometimes a piece of 
rock-crystal. As a rule, in engraving antique gems, 
and also those of the einque-cento lime, the tool 
ussd was worked by the hand, the stono to be 
eograved baing fixed. In more recent days, the 
reverse arrangement is foLowed, and in consequence 
the touch is less free and the style more mechanical. 
Tbe engraved work and the fijid of gems were 
pilished by rubbirg them with fine powders, 
i.ffimatite, or red oxide of iron, having been generally 
employed for this purpose. 
Paste was often legitimately used, but it naturally 
suggests the subj ect of fraud. The ancients were 
not iu( Xpert in this branch nf art, if it may be 
■■o called. One might say that the pair of green 
glasB palars in the temple of tho Tynan Hercules 
