ruby wedding 
(also ruby wedding anniversary)
noun
The fortieth anniversary of a couple’s wedding: it’s my parents' ruby wedding anniversary today...
- Eileen, 59, and her husband Cosnell had visited his native island of Carriacou in the Caribbean every year since they married and chose to celebrate their ruby wedding anniversary there.
- Celebrating her ruby wedding anniversary in September, Pam also plans to travel and see more of her daughter Rachel, 35, and son Richard, 37.
- Sadly, Mr Sanigar lost his wife Margaret after 48 years, and Mrs Burge's husband Bill died shortly after the couple celebrated their ruby wedding anniversary.