Could non-MS coins be graded by weight alone?

airplanenut

Barring the oldest coins where planchets may have varied in weight, basically every coin of a type has the same weight when struck. Since factors such as strike weakness don't affect the amount of metal in the coin, could a set of coins simply be graded, weighed, and have that standard used to grade all coins? This seems like it would work, except for the subjective aspect, because wear takes off metal, and reduces a coin's weight. Of course, this wouldn't work for errors such as clips, or MS pieces where no metal has been lost.

Or, would this idea just not work? Or would it bring about a new type of doctoring--hiding small weights on a coin?

Jeremy

ziggy29

Good question. I think a related, and possibly telling, question is:

How much weight does a coin lose in normal wear, and how much does that amount compare to the typical allowable variance in planchet weight?

Bochiman

No.

What if a coin has been "thumbed" repeatedly due to someone having a nervous condition (just to make this very easy and plain) and one side has almost MS quality and the other is "thumbed" down to VF or even EF.
The overall wear/weight may be that of AU.

You would be net grading.

So, if you want a coin graded, and graded well, no.

JrGMan2004

You would need highly sensative, precise instruments... plus, exact weight, probally down to a few hundred thousandths of a gram (Okay, maybe not that extreme, but you get my point) to the planchets, and then the exact weight ranges for each grade...

CharlesDarwin

Plus, someone could coat the coin in a thin film of Osmium and it would gain 3 or 4 grades. Especially with worn coins, lots of place to hide that Osmium dust.

In case you don't know...Osmium is the most dense metal on earth.

CD

JrGMan2004

I really think it's unfeasbile though... just because of the slight variations of weight from planchet to planchet... you could get a just slightly underweight planchet, and it be an UNC coin, but called AU58... I think in this set-up, you'd have to have some human oversight, and have a human finalizer...

ychange

interesting proposition, grading for the blind.

when you mentioned weight and the wear on coins, my first thought was of the often quoted average .715 oz. of silver per dollar on "junk" silver coins (circ. pre-65 dimes, quarters and halves). it's a place to start, as any MS grade non-dollar silver coins should have .72338oz. of silver per dollar. i guess they are saying on average circ. coins lose just over .008oz. silver per dollar, or about .26 grams. being only 90% silver, that'd be just under .29 grams of total material lost per dollar.

...not very much spread out over 4 quarters or 10 dimes.

another place to begin would be knowing the exact tolerance the mint uses for each type of coin. example, a penny today weighs 3.1grams, but to what tolerance? anywhere from 3.10-3.19? 3.100-3.109? how many potential "weight grades" would be throw off right at the start.

interesting proposition still, if you had sensitive enough scales, and had a large enough sample.

ychange

..one more thing, you'd have to clean them all before grading!

bosox

No. I specialize in Canadian large cents and a while ago did a min-study of weights of uncirculated 1858 and 1859 Canada large cents. They are supposed to weigh 4.54 grams. I weighed about 50 of them with a scale accurate to 0.01 grams. They varied from 4.3 to 4.8 grams. A graph of it looked like I used birdshot on the page. These were Canadian and 19th century, but I do not think the results are atypical of U.S. coins even into the 20th century,

MrEureka

APN - A variation on your theme might explain gradeflation. Perhaps TPG's grades are derived in part from the weights of the professional graders. After all, how much exercise can you get sitting in a chair in a dark room for 40 hours a week? Increasing waistlines would necessitate higher grades, of course.

LincolnCentMan

Nope... to much variance with residue or dirt clinging to the coin in the recesses.

David

mr1931S

In theory, it should be possible to grade a coin by weight if both sides have about the same amount of wear. My troy weight set is only practically useful to 1/4 grain or about 1/2000 oz. though.

I could probably detect the difference in weight between a "good" and "unc" but that isn't very useful. An extremely sensitive, and expensive, instrument for weighing to 1/10,000 oz. accuracy would be slightly more useful for grading but I have the feeling that even more precision would be needed to separate the "sliders" from the "uncs," or for that matter, the goods from the very goods, the very goods from the fines, etc.

BAJJERFAN

Could they be? Yes.
Will they be? Probably not ever.

Conder101

It has been suggested before and it can't be done. The tolerance allowance in the weight of the coins is large enough that you could wear a proper weight coin down to nearly VG before you get out of the tolerance range. And what if the coins original weight was ABOVE the standard? You coulld wear it down to say F to VF and it would THEN weigh what a new Unc was supposed to weigh.

Tolerances for current coins are

cent +/- .13 grams range is 2.36 to 2.63 grams spread is .26 grams or 10.4% of the coins weight
5 cent +/- .194 grams range is 4.806 to 5.194 spread is .388 grams or 7.8% of the coins weight
dime +/- .091 grams range is 2.179 to 2.361 spread is .182 grams or 8% of the cons weight
quarter +/- .227 grams range is 5.443 to 5.897 spread is .454 grams or 8% of the coins weight.
half dollar .454 grams range is 10.886 to 11.794 spread is .908 grams or 8% of the weight.

Don't have figures at hand for the dollar but you should be able to see the trend, the tolerance spread is about 8% of the coins total weight. So if the original weight can vary by as much as 8% obviously you are not going to be able to grade it by weight.

BAJJERFAN

You could grade silver dollars on the basis of how far you could throw one over or into the Potomac river too but it doesn't make sense. How could anyone think that an au 53 Morgan is consistently heavier or lighter thay an au 50 or au 58? Even if it was possible very few could ever afford the equipment necessary to accurately measure the difference. You don't just set up a balance capable of accuracy to +/- 0.000001 ounce on your computer desk or kitchen table.

Conder101

<< <i>Even if it was possible very few could ever afford the equipment necessary to accurately measure the difference. You don't just set up a balance capable of accuracy to +/- 0.000001 ounce on your computer desk or kitchen table. >>


I don't know about that. My balance was purchased surplus for $15 and is accurate to .0001 grams which is .000003 oz and occupies less than 1 1/2 square feet of table space.

Baley

you cannot weigh eye appeal.

longtimecollector

I recall reading somewhere where Morgans had to be weighed before they could be released from the mint........ But the weight was PER BAG.......... I also recall reading where there were "heavy" and "light" coins set aside for the purpose of bringing the bags up to their correct weight before shipping........ The idea of weighing a SINGLE coin to ascertain grade is just too far-fetched

wam98

Wouldn't the dirt and grim on this Morgan justify a higher grade than it really is, if grading by weight ?
How much dirt by weight would be on this coin ?

LindeDad

A big scratch may not remove any metal only displace it. What grade is the scratch worth? Sorry but I don't see that taken into account in your preposed system.

BAJJERFAN

<<"I don't know about that. My balance was purchased surplus for $15 and is accurate to .0001 grams which is .000003 oz and occupies less than 1 1/2 square feet of table space.">>

And what model would that be sir?

mgoodm3

you could probably get an average grade reasonably accurately, but only if you do it by the bag. need a big enough statistical sample to even out the natural variation.

BillJones

No. The mint does not maintain tolerances that allow one to grade by weight alone. Only minute amounts of medal need to be worn off or flattened to lower the grade of a coin. The differences in weight would not be large enough to assign grades to coins.

relayer

You could always upgrade by adding some weight to the coin then.

If you put enough stuff on you could get it up to a 70

cladking

As Conder and BillJones said the tolerance is much greater than the amount
of metal needed to be worn to change the grade.

Even the most worn coins generally have lost only 3% of their initial weight.

BAJJERFAN

I need to get me a bunch a those $15 surplus balances that can weigh fly turds one at a time. I kin make a killing on eBay.

Conder101

It's an old analytical balance, wood case, sliding glass sides etc. It's probably 70 years old or more. It came from the chem lab at a synthetic rubber plant. They decided to go to electronic scales and declared the old balances surplus. I picked it up for $15.

cladking

<< <i>It's an old analytical balance, wood case, sliding glass sides etc. It's probably 70 years old or more. It came from the chem lab at a synthetic rubber plant. They decided to go to electronic scales and declared the old balances surplus. I picked it up for $15. >>



Sounds a lot like mine. This one is probably a little older but was purchased at
a flea market as a gift for me. I doubt it cost any more.

BAJJERFAN

I thought you were talking about a current state of the art Mettler or Sartorius. Them old timers took forever and a day to weigh anything as I recall. A good condition one with wood construction could be worth quite a lot as a mantlepiece!!

MadMonk

No.

astrorat

As someone who has weighed over 300 twenty-cent pieces in various grades and did try and correlate weight to grade I can tell you that, at least with this series, there is no statistically significant correlation in grades of AG through AU. Coins in AG do weigh less than coins in AU, but the percentage difference for each coin is not predictable. Yeah, I'm a geek.

Lane

kieferscoins

There is your answer. You heard it from the geek himself

Good info Lane

Cameron Kiefer