FLAME FUSION (MELT PROCESS)
In 1902, the French chemist Auguste Verneuil developed the Verneuil process (flame fusion method) in order to grow synthetic rubies. The process involves dropping powdered chemicals through a high-temperature flame, where they melt and fall onto a rotating pedestal to produce a synthetic crystal. This method is still in use today and is the most common way to grow synthetic ruby or synthetic sapphire and synthetic spinel.
FLUX GROWTH (SOLUTION PROCESS)
The flux growth process is also used to create synthetic rubies and synthetic sapphires as well as synthetic emeralds. Flux is a solid metal which when melted will dissolve other materials in the same way that water dissolves sugar. As the dissolved chemical solution cools, the synthetic crystal forms.
HYDROTHERMAL GROWTH (SOLUTION PROCESS)
The only known process for creating synthetic quartz, such as synthetic amethyst, hydrothermal growth is a laborious and costly process that requires heat and pressure, replicating the conditions deep in the Earth under which natural gemstones are formed. Nutrients are added to a water solution and dissolved. As the solution cools, the synthetic crystals start to form.