Yes ,you may well be right Mike and as i mentioned my collecting interest may be different than most ,its just my own preferance that if i have two of something that are similar i will always keep the one with the most lustre.
NGC states that they don’t alter any surfaces during their conversation process, I often wonder what they do though, if joe bloggs dips a coin it’s cleaned, if NGC does the same it’s called conservation 🤷♀️