A purchase is made for proof coin gold or silver from the Royal Mint to have it graded. As we know these coins come with a significant premium, which you can understand for the woke that goes into the coin to get it to that standard has a proof coin. Its a thing of beauty.
So the coin goes off to be graded buy PCGS/NGC. On the coins return it has been given a PR69 or even PR68 and not the PR70 we wish for. Should you have the option to return it back to the mint has it is not flawless. There is not a standard for proof its the best the mint does.
Would a MS70 or MS70 first strike get a better return for you money than a PR69 or PR68. After paying that premium?