Might need to get some agate slabs at the next gem show! Artist Polke Sigmar's Agate Stone Windows designed for the Grossmünster in Zurich. Sigmar produced 7 cathedral windows made from translucent Agate found around the world.
No window over sink. Maybe an old window, painted panes - mount over kitchen sink. build a light box and place string lights around hidden inner edge to illuminate? Could also be done with old strained glass window.