Does she love roses? I recently purchased a Gold rose for my friend's mom and she really liked it. It's surely a unique gift. She will always remember you as this rose can be displayed and can serve as a memorabilia. If this won't work, I believe they also have plated rose jewelries. I found it on this link: www.anniversarygiftsbyyear.org/
I hope this helps! Good luck.
Petition for estranged Grandparents