Glass vase painted black

At first, I thought it was pottery. Even though the base is painted, when held up to the light, it's transparent and has a purple, reddish color. 7" tall. Do you recognize it?

 

'Amethyst glass'? Looks black except with light behind, showing then as purple.

This is something like it, sold on Ruby Lane. That one is poppy, yours is an iris. Do I detect a pattern?

 

Tiffin Iris vase. Ca. 1923. satin, nice. The color is normal. Its considered black. Black glass is made by putting a colorant in the glass, Amethyst is most common, but Heisey used cobalt, others used amber and other colors. The black was the goal.

 

Thank you both! There is so much to learn about glass. This is the first time I've seen a piece and I don't recall seeing it in my books in the past. My neighbor & I both had yard sales yesterday. I went over to see how he did and he said he was going to back his truck up and bring all the left overs to the dump. So I rescued a few interesting pieces including this.

I'm going to bring it back this afternoon and ask him to let me look before he "dumps" anything else in the future.

 

Tiffin also made a Poppy vase. very similar to the one above. These both came in about four or five colors. There were some late 1980s copies made, same mold. The original were machine blown and the edges L(at the top) are considerably thicker than the later, hand blown pieces. These later ones generally have a ground top edge.