The Science of Sapphires

Sapphire is a form of the mineral corundum – formed from crystallised aluminium oxide and has the chemical formula Al2O3. The colour of the sapphire is caused by different trace elements within the crystal which forms as a hexagonal bi-pyramid. While there are several possible causes for sapphire’s most familiar blue colouration, it is most likely tinted by the presence of iron and titanium in the corundum structure.

Sapphire is the second hardest gem found in nature, rating 9 on the 10 point Mohs scale of hardness. Sapphire crystals are formed under extreme temperatures and pressures either in metamorphic rock or during eruptive phases of volcanism and then ejected along with ash and other pyroclastic material in the early stages of eruption. Sapphire deposits are Lava Plains are basaltic sapphire, the result of the widespread volcanism that has shaped the landscape there. Not all volcanic activity, and not even every eruption from the same volcano, produces sapphire. While a wide range of colors are found in Lava Plains sapphire, in the course of the last 50 years the best sapphire produced from Lava Plains has become known across the industry for its rich deep blue. Some gemologists and gem cutters began to refer to gemstones from the area as being, ‘medicine bottle blue’, and ‘cobalt blue’. Recently in the trade these distinct blue sapphire have been called ‘Lava Blues’, the genesis of the Lava Blue Brand.