Hannay's experiments have been successful, and bis product proved to be minute diamonds. See a recent paper in the Mineralogical Magazine. (Hannay's Artificial Diamonds: F. A. Bannister and K. Lonsdale, Min. Mag., Vol. XXVI, No. 181, June 1943, pp. 315-324.) Hannay's minute diamonds were the result of success in his experiments.
RUBY. In 1837, Gaudin made artificial rubies by fusing alum at a high
temperature with a little chromium as a pigment. In 1847, Edelman made
white sapphire by fusing alumina in boric acid. Frenic and Freil made,
in 1877, crystal corundum from which small stones could be cut. Frimy
and Verneuil manufactured artificial ruby by fusing BaF2 and Al2O3 with a little chromium at red heat. There were also others working on the same fines.
VERNEUIL PROCESS. In 1902 Verneuil announced to the world that he
could manufacture ruby on a commercial scale. Other varieties of
corundum and spinel also could be manufactured. The manufactured stones
are known as synthetic gems, e.g. synthetic rubies, synthetic sapphire,
synthetic spinel. They are akin to the natural stones chemically and
physically except for certain features.
apparatus consists of an inverted oxyhydrogen blowpipe. Purified and
finely powdered alumina is kept in receptacles, the bottom being in a
fine sieve. The receptacle is tapped by a mechanism, when a small
amount of the powder falls into a flame and collects in a support. The
fused alumina takes a carrot shape, and is known as a boule or birne,
the broader part being uppermost. When the boule reaches 300-400 carats
the furnace is closed, allowed to cool for an hour and the boule is
removed with suitable tongs. Boules may go even up to 750 carats. If no
colouring agent is added, a white sapphire is produced.