More ideas from Zihoo
http://easterndesignoffice.tumblr.com/post/63074898619/atavus-sigmar-polke-agate-windows-in

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.