Question: 20 years is what anniversary?
Answer: These gifts vary in different countries, but some years have well-established connections now common to most nations: 5th Wood, 10th Tin, 15th Crystal, 20th China, 25th Silver, 30th Pearl, 35th Jade, 40th Ruby, 45th Sapphire, 50th Gold, 60th Diamond, and 70th Platinum.