However, the Verneuil process could also be used for the production of other stones, including blue sapphire, which required oxides of iron and titanium to be used in place of chromium oxide, as well as more elaborate ones, such as star sapphires, where titania (titanium dioxide) was added and the boule was kept in the heat longer, allowing needles of rutile to crystallise within it.
The Verneuil process can be applied to produce various gemstones, including blue sapphire, which necessitates substituting chromium oxide with iron and titanium oxides.  Additionally, more intricate stones like star sapphires involve adding titania (titanium dioxide) and heating the boule longer to allow rutile needles to crystallize within it.