Grading Room Question on PL and DMPL?

[Hack]

I have seen information on the reflection length of a PL and DMPL coins, for example a PL coin should have a minimum of 2" - 4" of clear field mirror reflection on both the obverse and reverse and a DMPL coin a minimum of 6".

 

My question is do the third party graders have a device or method to measure the mirror reflection on PL and DMPL coins in the grading room?

 

Is there any standard on how to measure the clear mirror reflection on PL and DMPL coins?

[AHFreak]

Every time I have seen a "grader" measure the mirrors they use their finger, and start close to the coin, and back away until they lose the reflection... however far they got before losing the reflection is how deep the mirrors are.... I highly doubt that is a "standard", in fact, I doubt there is a standard way to measure the depth of mirrors. Its probably one of those things that you just do the way you were taught....

[coinman1794]

I think it was David Lang who once said, here on the forum, that he uses the reflection of the tip of a pen to measure the mirror depth.

 

Because PL surfaces appear on many different coin types, which have many different surface irregularities, it is impossible for one standard to be applied to all coins. A PL mercury dime, with its tiny, bowl shaped fields, will not reflect light the same way as a Morgan dollar, for instance.

[mumu]

I think it was David Lang who once said, here on the forum, that he uses the reflection of the tip of a pen to measure the mirror depth.

 

Because PL surfaces appear on many different coin types, which have many different surface irregularities, it is impossible for one standard to be applied to all coins. A PL mercury dime, with its tiny, bowl shaped fields, will not reflect light the same way as a Morgan dollar, for instance.

 

I would not want the tip of a pen going near my coins.

[RWB]

The reflection of the helical rising of Sirius, that is the standard of measurement -- has been so since pharaonic times.

[physics-fan3.14]

The reflection of the helical rising of Sirius that is the standard of measurement -- has been so since pharaonic times.

 

I haven't seen any prooflike coins from the times of the pharoahs, but I have seen some from the Romans.

[Raisethis2]

The Romans had much smarter slaves.

[johnny9434]

why dont we ask ngc to come in and chime in on this topic? just asking

[RWB]

Ah, yes. They could ring the famous St Augustino chimes at vespers.

 

Seems prudent to see what the NGC folks have to say....it is their shop.

[Nutmeg Coin]

They have definitely tightened up on the PL, etc., standards which seems across all serious grading companies.

[Lucky One]

I have always used a piece of bright white paper (to help reflect more light) with large bold print on it, like an info poster that you would see posted on a telephone pole or bulletin board. Be sure to brush it off before placing the coin near it, and use great caution as you handle the coin because it will hairline easily. White gloves are necessary and they should be brand new, right out of the package, to avoid getting any fine grit from every day life on them. Stand the coin on it's edge at the farthest point from a line of the bold print where the print can still be read in the mirror- this is the true depth of the mirror.

 

Other suggestions posted here, like the one mentioning the vast differences in the qualities in the fields of different series, should seriously be taken into account.

 

There is nothing like the thrill of finding a deep prooflike in ANY series. It was once an obsession with me, but my problem is I want to find a lot of what I collect and there are NOT a lot of gem prooflike coins out there to find, period. It takes a patient collector to build a significant set of anything in true prooflike.

 

Please post photos of your finds here, there are a lot of lovers of the genre!