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192
GEMS.
that, in his time, carbuncles were made of glass so like the real that it was only possible to know the differ­ence by the hardness.
In some ancient jewels, as in Eastern ornaments, rubies are seen very roughly worked, but well polished and pierced from side to side, with grave injury to the beauty of the gem.
In the Hertz collection there was -a necklace com­posed of rubies and rough emeralds of excellent quality and colour, and of the size of small beans, pierced and strongly fastened together with a golden thread.
I have never yet seen Oriental rubies engraved which could with certainty be called antique.
I have tried many times to have some engraved, but, in spite of the best efforts of skilled artificers, the results were but mediocre.
Wherefore, Lessing, a scientific German, and the Count de Clarac, a French archaeologian, having, as the result of their long experience, declared as gene­rally modern all the intagli on corundums which were asserted by others to be antique, I adhere to their authoritative opinion with regard to the Oriental ruby.
2. SPINEL RUBY.
The spinel is an anhydrous aluminate, having a base of magnesia, zinc, and iron, crystallized in regular octahedrons differently modified, and sometimes in tetrahedrons.
In general, the planes of its crystal are more regular