ARTIFICIAL PRECIOUS STONES. 
BY W. G. HOWGRAVE. 
S INCE Sir Humphrey Davy first discovered the diamond to 
be pure carbon, unmixed with any other substance, various 
attempts have been made by chemists to produce it, and other 
precious stones, by artificial means ; and it may not be unin- 
teresting- to glance at some of these essays, and to see how far 
they have been attended with success. 
But little progress has as yet been made towards the dis- 
covery of the means of imitating the natural diamond, men of 
science having hitherto been baffled in all their efforts to find 
a substance capable of dissolving carbon, the chief constituent 
of that crystal ; and indeed, until Despretz succeeded, by the 
agency of electricity, in actually producing minute diamonds, 
the manufacture of this precious stone seemed as chimerical as 
that of the philosopher’s stone, so perseveringly sought after by 
the ancient alchemists. Despretz found, that by passing a 
powerful galvanic current through a point of charcoal over which 
a platinum wire was suspended, the charcoal was volatilized 
and deposited on the wire in the form of minute crystals, 
which, on examination under the microscope, proved to be 
true diamonds. Since this discovery no further advance has 
been made towards the solution of this interesting problem. 
The search after the diamond having proved so unsatisfactory 
in its results, attention was directed to a class of stones almost 
as simple in them composition going under the generic name 
of corundum. In order to understand the experiments that 
were made, and the difficulties attending them, it is necessary 
that a clear idea should be obtained of the composition and 
distinctive characteristics of the stones belonging to this class. 
I will therefore, in as few words as possible, give a description 
of their nature and properties. 
The ruby, sapphire, oriental topaz, and several other precious 
stones, are all merely coloured varieties of a mineral called 
corundum, or white sapphire, the composition of which was 
stated by Chenevix to be alumina, mixed with a small pro- 
portion of silica and oxide of iron. Dr. Thomas Muir and 
