2006-P 20th Anniversary Silver Eagle NGC Reverse PF70 Proof 70
Only about one quarter of the 2006-P Reverse Proofs Dollars are high enough quality to make PF-70 at NGC. Equally interesting is the fact that the 2011-P Reverse Proofs grade very well and well over half of them are making ultra grade. This has created a situation where the 2006-P is becoming extremely hard to find in PF-70 in the face of high demand.
Coins that mature well tend be popular issues that are either low mintage or grade poorly and have public demand that marches on long after the dealer inventories have had time to disipate. This coin is a beautiful case in point.