48 NATURAL HISTORY OF PRECIOUS STONES, &c.
afterwards
gave to Trajan on appointing him bis colleague, and with which the
latter some years later rewarded the eminent services of Hadrian in the
second Dacian War, as Spartian records, thereby tacitly acknowledging
him for his successor in the Empire.
A
few rings also have come down intact to our times, which show what was
the appearance of this of Nerva's, or of the one set with the
" Adamas notissimus et Berenices In digito factus pretiosior,"
that
doubtless had flashed in St. Paul's eyes on the momentous audience
before the Jewish queen and her too-loving brother in their " great
pomp," and which afterwards, a souvenir of Titus, graced the
finger of the imperious lady in Juvenal's days. The Hertz Collection
possessed a well-formed octahedral Diamond, about a carat in weight,
set open in a Roman ring of unquestionable authenticity. The Waterton
Dactyliotheca, in its almost unlimited extent, comprising the rings of
all nations and ages, furnishes a yet finer example of the Diamond in
its original setting ; a ring of a singular fashion, apparently dating
from the Lower Empire, for the head is much thrown up, and has the
sides pierced into a pattern, the " opus interrasile," so greatly in
vogue during those times. It is set with two diamonds of (judging by
the eye) a carat each ; one a perfect octahedron of considerable
lustre, the other duller and irregularly crystallised. Another such
example might be sought for in vain throughout the largest cabinets in
Europe.
The
Romans in their estimation of this gem were guided by the Indians, who
have ever given it the first rank amongst jewels ; the Persians,
however, in the thirteenth century, placed it fifth; after the Pearl,
Ruby,