Congratulations! It takes a lot of perseverence to get a qualification in something, so don't hide your diploma where it'll gather dust and don't frame it with something from Crazy Clark's. Show it off in a beautiful custom made frame. If nothing has a lot more credibility than "just a piece of paper".

But being a piece of paper, it's prone to the usual deteriation that is caused by oxygen, ultra-violet light, and just general wear and tear. Trapped behing our special preservation glass, your certificate will still look as lustrous in 20 years as it does today.