Some years ago, I took a museum course about working with seed beads on fabric. The teachers were Delica seed bead wizards, using them to create tiny portraits, and embellishing with them in the most astonishing ways. These earrings by Shayna Illingworth, which use the glass Delica beads, as well as Leland green slag set in sterling silver, remind me of the art created by my teachers.
Leland blue slag is a manmade material that was actually smelting waste tossed into Lake Michigan; I am assuming that this is a similar composition (which comes from heated iron ore and borax, as well as other components). It just confirms that beauty is definitely in the eye – and the ear – of the beholder.