Black Goldstone

My designer cabochons are made from a black material I purchased at an estate sale. I researched to find out where it came from. I found nothing listed that ever showed a black Goldstone was ever created. I've seen dealers selling what they said was black goldstone but when I got it, it was just a dark blue. This material flashes beautifully as it turns in the light. I took my pictures at all angles. The white spots in the pictures are crystals and hundreds of them are not seen in the pictures.