Question about staining clay...

Hi all! Last week my husband and I were heartbroken to have to put our German Shepard down. The vet's office gave us this heart shaped clay cut-out of her paw print, and now that it's completely dry, I'd like to put a glossy stain over it to preserve it better. I don't know much about clay, so was wondering if anyone knew what was best to do this with? Thank you for your help!!