Black (or Purple) Goldstone,

or Aventurine glass is a human-made stone.  This stone is made with tiny crystals of metallic copper that require special conditions to form properly and mixed with glass.  This is a very sparkly stone.

They call this Black Goldstone, however, the black glass has a purple look to it, thus it is also called Purple Goldstone.

To use:  encase in a clear glass.  (try not to touch the flame directly to the stone, as this will create blackened and dull spots)

Pull out into a stringer.  (thick or thin, depending on how you want to use it)

This pulled stringer can shock when using it, so a good practice is to preheat (place in kiln prior to use).

Fun Fact: Goldstone was first created in 17th-century Venice by the Miotti family, master glassmakers on the island of Murano

Note: not compatible with Borosilicate.