Diamond lost in Indesit without filter.How to find it?

I have just lost a diamond out of my ring, and remember it catching on the duvet covers before they went in the wash. My Indesit 462W has no external filter as it's supposed to be self cleaning. Is there an internal one where the diamond might be? And how do I get to it? I've drained all the water into a bucket and sieved it and it's not there. Any ideas?