igotaratidea

What if you added the ashe as a last step?

A layer of ashe burned in after the piece has been blown.

They might have gotten the idea from here...

https://en.wikipedia.org/wiki/Karen_Silkwood

Nuclear plant union activist murdered by radiation poisoning planted in her home.

Spy Game is a pretty good movie too.

http://www.nytimes.com/1996/11/12/world/spies-can-t-even-trust-the-other-side-anymore.html

http://foreignpolicy.com/2014/08/18/spies-like-us-germany-spies-on-allies-too/

http://www.securitycurrent.com/en/writers/mark-rasch/the-unwritten-rules-of-washington

I was thinking the same thing.

If you still want to do something similar you can do ceramic.

Not as cool as glass but you can incorporate the ashes more easily.