What does a grading service do?
Three things: authenticate the coin as genuine, assign a numeric condition grade from 1 (barely identifiable) to 70 (flawless), and seal it in a sonically welded, tamper-evident holder with a certification number you can verify online.
For the collector market, this infrastructure is essential, it lets rare coins trade sight-unseen between strangers with confidence in what will arrive.
Why do grades move prices so much?
Because rarity concentrates at the top. For genuinely old coins, the jump from grade 64 to 65 can multiply a price, since few survivors exist in top condition. The grade is the market's shorthand for scarcity.
The same math does not transfer to modern bullion: millions are minted, thousands grade 70, and the 'perfect coin' premium often evaporates at resale. A grade describes condition, not investment merit.
How do grading services show up in practice?
Two checks before paying a graded-coin price: verify the certification number on the service's own website, and look up actual recent sale prices for that coin in that grade. If the dealer's quote sits far above verified market sales, the holder is authentic and the price still isn't fair.