Diamonds?

Queen Victoria celebrated her Diamond Jubilee after only 60 years on the throne, but I suspect that's because she knew she wouldn't be around for the 75th. Traditionally, though, a 75th anniversary is celebrated with diamonds--which, I'm sorry to say, I won't be giving my dad for his 75th birthday today. Caroline has already gotten the relevant historical context, so I'll just add my birthday wishes to hers--happy birthday, Dad!