Victorian Solid Blue Cameo

by Karen
(Massachusetts)

Hello, I'm hoping you can help me. I have this lovely cameo and I'm puzzled about the material. At first I thought maybe some sort of blue lava, then I thought it might be porecelain, like a Wedgwood Jasperware cameo, even though it's a solid blue. Feels cold and teeth taps like glass but I don't think it's glass. Can you help ? Thank you for any and all information.