Acceptable weight variance?

Discussion in 'Coin Chat' started by Zzyzzyth, Feb 18, 2010.

  1. Zzyzzyth

    Zzyzzyth Junior Member

    Is there a "rule of thumb" when it comes to weighing your coins as far as the variance from the known weight?

    For example, I just bought a BU 32P Washington. When I got it home and weighed it, it was only 6.25 grams instead of 6.33. Surely, there is no reason to try and fake a 32P (or is there?), but would this be cause for concern?

    My 32-D weighs 6.3 grams. I just assumed that this would be in the variance range, but never really gave it any serious thought before today, other than if it weighed 5.8, or 7.4, or something ridiculous, then I'd be alarmed.

    So, at what point do flags go up?
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  3. Vess1

    Vess1 CT SP VIP

    Where'd you come up with 6.33 grams? The proper weight IS 6.25 grams.

    As far as what tolerances they can have nowadays, I'm not sure. They can be pretty bad. But BU examples should be very close if not dead on. Looks like yours is.
    Even if it was off by 0.08 grams, that seems like a large number but is only 0.0025 of a troy oz or 1.23 grains. That is a very minute amount. There are 120 grains in 1/4 of a troy oz.
  4. Zzyzzyth

    Zzyzzyth Junior Member

    I think I got it from PCGS website. When I went to check just now, it said 6.30 grams. So, now I don't know.
  5. dctjr80

    dctjr80 Senior Member

    Since scales are usually allowed to be off by .1 grams I usually am not alarmed if it is .1 grams up or down IMO.
  6. dctjr80

    dctjr80 Senior Member

    although my alarm meter is more sensitive to this the rarer the coin, as to like you said, the likelihood of anyone wishing to really waste the effort to create a great looking fake, also this is only IMO.

    GDJMSP Numismatist Moderator

    The rule of thumb you are looking for is 1%. More than 1% over or under - and there is reason to be suspicious.
  8. bqcoins

    bqcoins Olympic Figure Skating Scoring System Expert

    unless the coin is worn, and I mean really worn, I've got a couple of coins that are borderline AG/FR that have lost nearly 20% of their weight due to wear or environ damage whatever. But when it comes to BU coins like Doug said 1%, up or down is all that I'd give it.
  9. dctjr80

    dctjr80 Senior Member

    Thank you!

    I will remember this answer and thank you for the knowledge.
  10. mpcusa

    mpcusa "Official C.T. TROLL SWEEPER"

    What are the rules of thumb in evaluating a coin, Weight, diameter,Thickness
    Anything else??
  11. Vess1

    Vess1 CT SP VIP

    The redbook and every other website lists 6.25 grams.

    If there's generally a 1% allowable variance, than on this quarter that would be +/- 0.0625 grams, obviously.

    My pocket scale will weigh down to one grain accurately, after the quick calibration, and that's as far as I can trust it. You're probably pushing the accuracy limits of most scales at this point.

    FWIW, there will be fakes that have accurate, indistinguishable weights and the ones that don't should be fairly obvious. More so than 1% most likely.
    As someone else stated above, worn examples lose a lot of weight (into the 0.1+ gram range) fairly easily. BU examples should always be very close to spec.
  12. Zzyzzyth

    Zzyzzyth Junior Member

    Thanks for the input as always. I would have never guessed 20%!

    I appreciate the 1% response, sounds good. No wonder it takes a lifetime to learn the ins and outs of coin collecting. I should have started in my previous life!
  13. Vess1

    Vess1 CT SP VIP

    I think 20% is on the high side. Especially for modern stuff. Coins today simply don't circulate that much or for that long anymore. A lot of stuff used to cost a nickel or a dime in the past. So they circulated that much more. Now everything starts at $1+ and nobody likes counting out exact change or carrying it.

    I'd say the average well circulated Mercury dime is 5 to 6% underweight from the metal that's been worn off. That's common. Some of the older coinage circulated a lot more and REALLY got worn down. That's why they have the AG grade.

    When you're talking about tenths and hundredths of a gram, and a coin has been worn flat, to the point where all that's left is the outline of the central design, that really shows up on the scale.
  14. GDJMSP

    GDJMSP Numismatist Moderator

    No, they absolutely do not lose a lot of weight from wear. In fact very worn coins, even those down in the AG FR range do not lose anywhere near to 20% of their weight due to wear. The most you could expect to lose due to wear would be less than a fraction of a gram even on large coins like Morgans.

    Now environmental damage, like corrosion, yes they could lose 20%, but that would be extreme. But not from wear - never.
  15. dctjr80

    dctjr80 Senior Member

    I would have to agree with GDJMSP, I have too heard that the metal of the coins details, more or less get pushed down into the coins, not lost from the coin, so wear would not cause a loss of weight, IMO
  16. Vess1

    Vess1 CT SP VIP

    It depends on your definition of "a lot". In looking at the math above, several percent of wear only amounts to fractions of a gram as you say. Which, you can argue isn't very much at all. I agree.

    But most heavily worn coins will be out of their spec weight by upwards of 0.1 grams or more. Quite a bit when they're being analyzed to the hundredth.
  17. GDJMSP

    GDJMSP Numismatist Moderator

    To put it into perspective, try thinking about how much orifinal weight a heavily worn retains - instead of what it loses. Heavily worn coins will retain 98% or more of their original weight.

    Kind of puts a different light on it when you look at it that way.
  18. Zzyzzyth

    Zzyzzyth Junior Member

    When I go to PCGS website, click on price guide, go to Washington's, and click on their ID number, it lists the specs as 6.30 grams. Did they typo? And should I now be concerned with my 32-D?
  19. GDJMSP

    GDJMSP Numismatist Moderator

    Probably - an no.
  20. Conder101

    Conder101 Numismatist

    Mint spec for a new silver quarter 1873 - 1947 is 6.25 grams +/- .097 grams. For 1948 to 1964 the weight is the same but the tolerance loosens to +/- .194 grams. For clad coins the specs loosen even more. The CuNi clad are 5.67 grams +/- .227 grams, and the 40% silver clad bicentenials are 5.75 grams +/- .220 grams.

    A complete table of the specs can be found in the Coin World Almanac.

    I would say no. Most collectors that have scales only have ones that are accurate to one decimal place. A 6.25 gram coin weighed on a scale accurate to one decimal place will typically show 6.3 grams. Rounding you understand. If the coin weighed 6.23 grams it would show 6.2 grams
  21. Zzyzzyth

    Zzyzzyth Junior Member

    I have the Digi-Weigh scale that measures to 100th grams.
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