Uh... NFTs are records on the blockchain... So if your diploma is an NFT, it is on the blockchain and can't be faked.
Good God you can't be that gullible surely?... What part of
"x can be counterfeited / faked BEFORE it's placed on the blockchain" are you persistently mentally struggling with? Back in the real world, NFT's are nothing more than a "claim" which may or may not be any more true or valid than any other legal contract or even a scribble on a piece of paper. Being on the blockchain just means the piece of digital paper the "claim" is written on isn't counterfeit, not that what's being claimed is valid / truthful or genuine in any way or even that a competing NFT claiming someone else is the owner can't also be generated and stuck on another bit-identical copy of the same digital content (being "first" to be NFT'd doesn't guarantee truth either)...
Perfect real world example :
An NFT was recently sold of the "original" Disaster Girl meme photo for $500,000.
Q. Why is that 'worth' $500k vs "free" for the 100m other people who've viewed it?
A. The fallacious and delusional belief that the NFT somehow
"guarantees it's the original photo". Except it doesn't. Where's the proof the photo was the original and not just another copy? Does the family even have the original 16 year old digital camera + SD card, and do they work? Given the age of the photo and the nature of flash storage vs cell charge loss, it's guaranteed what was really NFT'd was "a copy of a copy" of the photo taken from a backup drive rather than the original 2005 camera's SD card, with a
"there you go, there's the 'original', look an NFT said so" advert slapped onto it.
"An NFT proves it's the original". No, it really doesn't. In fact not only does the NFT fail miserably at proving that, it fails at even proving that the original file even exists anywhere on the planet and that the person who handed over $500k didn't just get sold another very ordinary copy like the 100m other people who viewed the meme over the past 16 years. The family could have downloaded it at random from Google Images, cleaned the metadata off then stuck an NFT on it afterwards, and you wouldn't have known any different thus rendering the whole claim and point of the "originality" NFT claim completely and utterly worthless.
People like you seem to struggle with the basics -
Real-world verification is a *process* not simply an object that can be replaced by a token. Eg, all sorts of checks take place when exchanging property, checks on purchasing party for bankruptcy, money laundering, check on selling party for whether property has a legal charge / mortgage over it, all of which involve
centralised databases for a reason.
"Everything needs to be decentralised even when it makes zero sense" is 9 times out of 10, nothing more than Alex Jones style "Doom Boner / Armageddon Porn" conspiracy theories and NFT's are the perfect modern "Poster Child" in 'solution looking for a problem' that exist primarily to sell a novelty to some very gullible rich people cheered on by clueless conspiracy cultists.
And this is NFT BS in a nutshell - it's the overhyped irrational worship of a tokenised 'receipt' that's no more reliable, accurate, truthful or genuine at verifying the object it claims to certify than any "Certificate of Authenticity" on any ordinary piece of paper but is dressed up to be glamorous because "muh blockchain" thing is still going through it's dot-com-bubble style novelty phase. And the bursting of that ridiculous fraud-saturated bubble can't come soon enough...