Cause of Proof-Like MMIX Gold Double Eagles

[RWB]

Some of the new MMIX double eagles have somewhat more reflective fields than normal pieces. This does not come from “polishing” the dies or other intentional die modification.

 

The pure gold blanks are polished so they can produce the best possible coin when struck. However, with use, the mirror-like planchet surface is transferred to the working die. This results in a “PL” coin instead of the intended satin surface.

 

[physics-fan3.14]

Interesting. So does this mean that PL UHR's are not rare or worth a large premium? This also implies that UHR prooflikes come from a later die state, not the initial strikes as do typical PL coins. Interesting....

[BillJones]

I'd say the P-L pieces are worth a premium, and I wish the mint had sent me one. Seriously I think anything that makes these coins more attractive, like great luster and fewer die polishing marks, which is what I got is a big plus.

[Schatzy]

Well I looked at the pop report and there are 3482 graded non-pl and only 140 PL coins. So why aren't there more PL coins?

[RWB]

So why aren't there more PL coins?

 

As noted above, it takes many normal strikes to transfer the planchet’s polished surface to a steel die. Therefore, dies that have been altered in this way are close to the end of their life.

 

[WoodenJefferson]

perplexing

[relicsncoins]

Mine is PL, but its raw.

[Coagman]

RWB,

Thanks for the explanation. Is this theory consistent with the fact that some PL examples have die polish lines evident in the fields? Could it be a combination of both the polished planchet transfer effect that you mentioned and a direct polishing of the die at a late state?

 

 

[Coagman]

I have been tracking the number of PL coins graded by NGC since the census data were first released. In mid-May, only 2.05% of UHRs were designated as PL. In early June, the percentage increased to 2.56%.

The most recent census (July 9) shows a PL percentage of 3.87%. A total of 140 PL’s have been graded by NGC including both ER and non-ER (74 in MS69PL and 66 in MS70PL out of a total of 3622 coins).

As I mentioned in another post, I suspect that coins with reflective, PL surfaces are being preferentially submitted to NGC since PCGS does not offer this designation.

Below is an image of an MS69PL ER. The fields are definitely more reflective than a typical UHR.

[RWB]

The cumulative effects planchet surface transfer to a working die is independent of any intentional touchup or other maintenance done on the die.

 

What we do not see are coins rejected by the inspectors.

 

[RareSov]

Hmm very interesting theory, is it just theory or do you have proof ?

 

I want PL, they are worth more ! want a 70 really.. but 69PL would do nicely.

[RWB]

Depends on "proof."

 

I've examined coins, planchets, the striking process used, etc, but have not been able to follow a single pair of production dies from first use to condemnation. It's a reasonable conclusion based on current practices and past practices.

 

A similar phenomenon accounts for non-cameo proofs in earlier series such as Franklin halves, evolution of PL dollars to frosted, etc.

 

The only other proposal is deliberate polishing of dies. But, that is contrary to the stated goals of the chief engraver and director. It also neither accounts for gradations of the semi-PL effect, nor for the surfaces of coins struck from new dies.

 

 

 

[Schatzy]

I find it interesting that if the PL coins are from the dies at the end of their life can still hit the 70's.

 

RWB thanks for the informative post.

[RWB]

"MS 70" is supposed to be flawless as the coin comes from the dies (at least by one of Sheldon's definitions) - it really does not say anything about the condition of the dies.

 

Personally, "MS 70" and the rest of the subjective hair-splitting, is hot air and guesswork. But some collectors live for the paper label....so, they find enjoyment in such things, which is good.

 

[RareSov]

I did think a bit like that for a while, but the 70's are superior coins, no doubt

 

Many years down the track, we'll see..

[PerryHall]

Some of the new MMIX double eagles have somewhat more reflective fields than normal pieces. This does not come from polishing the dies or other intentional die modification.

 

The pure gold blanks are polished so they can produce the best possible coin when struck. However, with use, the mirror-like planchet surface is transferred to the working die. This results in a PL coin instead of the intended satin surface.

 

Sounds like you are saying the polished mirror-like planchets burnish the dies until they have polished surfaces. Interesting observation.

[RWB]

Right (except "burnish" is not the best term - a dull finish would be imparted if the planchets were dull.)

[RareSov]

Great observation anyway, no wonder the % is so low !

 

They strike a hell of a lot more than 500 per die set of normal coins and retain Ultra Cameo proof appearance, right ? so if it was initial die freshness, you would expect a higher than 2% or whatever