Vintage moulded sky blue glass cabochon brooch set in silver tone, beautiful detail, extremely unusual

Vintage silver tone and moulded glass large oval brooch. I have seen a lot of vintage jewellery and I have never yet come across a brooch like this. It consists of a silver tone open-backed mount with pretty, textured claw settings, holding a large oval cabochon of cobalt / sky blue, beautifully moulded glass.

The glass piece is moulded / pressed / poured in a really unusual and stunning swirling design, but the brooch is unsigned. The blue glass really glows as the light shines through it, it is very striking. It is in very good vintage condition.