These are lab created Czochralski pulled yellow sapphire facet rough. Pieces are available as sawn pieces by their gram weigh, either as blocky pieces ideal for versatile cuts or corners which are good for trillions.
My friend Arya is a huge lab crystal fanatic. He was trying to have a high quality green cobalt sapphire grown, but unfortunately everything went wrong and it ended up being almost entirely cobalt-free (hence the name, 'nobalt' or 'Arya's Folly'). Fortunately it was also inadvertently contaminated with nickel, and after oxidation it turned a rich golden yellow color! These cut gorgeous gems with a rich golden yellow color--even if it wasn't what was intended it still came out as very high quality sapphire rough.
