These are pucks and rods of sapphire ceramic which were grown as feedstock for growing optical grade sapphire crystals. They are essentially polycrystalline lab sapphire--the multi-step growth allows for greater purity which is essential for making ultra high end industrial sapphire. It is mostly composed of interlocked crystals of microscopic sapphire, which gives it is exceptionally strong sparkliness. If you want larger quantities drop me a line!
