effected by closely enveloping the stone ready cut and polished in
German tinder, firmly bound with fine wire ; this being kindled, when
thoroughly burnt out the colour of the Topaz will be found converted to
a clear rose without the least detriment to its original texture or
polish. But if the roasting be carried too far it extracts all colour,
and the stone assumes the whiteness and lustre of the Novas Minas sort,
the so-called " Slave's Diamond." An extremely rare variety of the
Brazilian Topaz, shows an indigo blue, but with a peculiar tint that
ever at first sight distinguishes it from the Sapphire. The finest
specimen in existence belonged to Mr. Hope, weighing 1-1/4 ounce, and
was brought by Mawe from Brazil : previously it was unknown in Europe.
The mine had only been discovered during Mawe's residence there. The
Siberian blue is paler. The White Topaz, better known as the " Novas
Minas," is perfectly colourless and very brilliant. It greatly
resembles the Diamond itself in every point except its iridescence, and
has not unfrequently been substituted by fraud for its precious
companion in the mines.
in his commentary upon Baccius, mentions (sub Topazio) that Hadrianus
Guilelmus of Naples possessed one engraved in antique Boman letters
WORDS NATVRA DEFICIT . F0RTVNA MVTATVR . DEVS OMNIA CERNIT :
is the only example I have met with of a spell couched in that
intelligible language. In the Blacas Cabinet is a good head of the poet
Horace on a stone described as Topaz in the catalogue, but more
probably a yellow Beryl.