You send an item to a grading company. They confirm it's genuine, score its condition and seal it in a labelled case, which usually makes it easier to sell.
Step by step
1Check the estimated upside on the item — the difference between raw and graded value.
2Subtract grading and shipping costs. If little is left, grading isn't worth it.
3Protect the item first. Don't clean it, press it or repair it.