Jasanche
Joined: 14-Sep-2016
Posts: 604
Posted: 17-Nov-2016, 19:49
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Posted: 17-Nov-2016, 19:49
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Hello all,
I am very new to this hobby, but it has hit me hard! I love reading the numista forum and thank you all for sharing so much of your knowledge.
Here is my first question, but surely not the last, to this forum:
how much deviation from the listed weight of a coin would you allow before you become suspicious?
I am pretty sure that the type of coin and the condition (circulated vs incirculated, worn vs AU) has to be taken into consideration, but what would be a good rule of thumb? I've gotten a scale that measures to the hundredths +- 0.01, and usually measure my coins at least five times...
If this question has already been posted, please let me know!
John
Sjoelund
Joined: 28-Mar-2012
Posts: 12379
Posted: 17-Nov-2016, 21:28
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Posted: 17-Nov-2016, 21:28
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Hi,
since I weigh the coins in my collection (I'm collecting by year and mint mark) I can show you that a variation of plus minus 5% is OK depending on the wear of the coin.....
Ole
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com
aaronmgd
Joined: 9-Jan-2013
Posts: 892
Posted: 18-Nov-2016, 01:07
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Posted: 18-Nov-2016, 01:07
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It depends on the coin. 5% on certain larger coins is not a good sign. 5% on smaller coins is acceptable. but it really does depend on metal type, coin size and wear. a Morgan dollar with a 5% variance is not a good sign unless there is very very heavy wear.
I sell my Duplicate or Un-Needed coins on eBay:
https://www.ebay.com/str/coinsandmorenj.
neilithic
Joined: 28-Mar-2011
Posts: 7493
Posted: 18-Nov-2016, 01:12
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Posted: 18-Nov-2016, 01:12
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It does really depend on the type of coin, a lot of the older coins the quality checking wasn't up the standards it does with modern coins, so a difference of 5% in a 200 year-old coin is far more tolerable than a 5% difference in a modern coin
Mark240590
Joined: 3-Jul-2012
Posts: 5612
Posted: 18-Nov-2016, 01:16
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Posted: 18-Nov-2016, 01:16
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As my man Neil says it depends on the coin and even where it's minted sometimes
Jasanche
Joined: 14-Sep-2016
Posts: 604
Posted: 18-Nov-2016, 01:36
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Posted: 18-Nov-2016, 01:36
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OK, so let's narrow it down by stating a type and condition:
What would be the tolerance for the 1 oz Mexican silver libertads from 1982 to present, in bu condition? the weight is listed as 31.1 grams...
On the other side of the spectrum, what would be the tolerance on a Mexican 1882 copper-nickel 1 centavo in fine condition? The weight is listed as 1.96 grams...
So, as this post may hint, I like Mexican coins...
John
pnightingale
Joined: 27-Jul-2011
Posts: 5383
Posted: 18-Nov-2016, 02:54
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Posted: 18-Nov-2016, 02:54
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Modern bullion coins should have no noticeable deviation. "You had one job....."
The further back you go, the more given weights should be treated as polite suggestions rather than hard and fast rules. The technology in use today is precise and high speed compared to the primitive machinery of only 75 years ago. Some weeks ago there was a most interesting movie posted showing the inner working of the Royal Canadian Mint in the 1920s which you will find useful if you can track it down.
Bigger coins lose more of their weight in circulation than smaller ones, but even that generalisation has to be viwed through the lens of numismatic savvy because the everyday business of the day was conducted in Farthings and Pennies rather than Sovereigns and Guineas.
Provincial mints and those from countries outside of the European industrialised belt had looser specifications. Coins from the pre industrial period would often change composition even within the same series depending on the availability of the materials. You will notice many coins are described as "billon" which is an unspecified mixture of silver and base metals. There is simply no way to give a precise weight for such coins, the best we can do is to offer a range based on surviving examples.
Non illegitimis carborundum est. Excellent advice for all coins.
Make Numismatics Great Again!
Jasanche
Joined: 14-Sep-2016
Posts: 604
Posted: 18-Nov-2016, 05:52
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Posted: 18-Nov-2016, 05:52
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OK. I understand much better now.
But my question still lingers in my head. The two different types of coin were mentioned as extremes and because i have a couple of them. So, for example, i have a 2011 silver libertad that weighs 31.00 (0.10 gr under) and a 2013 that weighs 31.16 (0.06 gr over)... So, whereas every site i've seen recommends you get a scale that can measure to the 0.00 with a +-0.01 of accuracy, is this then noticeable deviation on a coin that should be exact?
But I get it: with older coins that have been circulated, especially from countries with multiple mints (although the 1883 coin was minted at the Casa de Moneda de Mexico, the oldest in the Americas, which I hope means that they knew what they were doing by the late 1800's) may have greater deviation. But, what would be the limit? 5%? What is the range you suggest?
Sjoelund
Joined: 28-Mar-2012
Posts: 12379
Posted: 18-Nov-2016, 09:57
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Posted: 18-Nov-2016, 09:57
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Hi,
here a table showing the Danish 10 oere in old and new versions. You can draw your own conclusions out of it.
For the first, km795, the official weight is 1.45 grams, for the second, km860, the official weight is 3.00 grams.
Ole
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com
Idolenz
Joined: 13-Jul-2013
Posts: 6591
Posted: 18-Nov-2016, 12:08
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Posted: 18-Nov-2016, 12:08
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You also have to keep in mind that your scale has a certain tolerance and might not be completely calibrated and it is influenced by temperature changes and magnetic fields.
Sjoelund
Joined: 28-Mar-2012
Posts: 12379
Posted: 18-Nov-2016, 12:15
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Posted: 18-Nov-2016, 12:15
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Hi,
with these tools, I'm inside the 0.01 unit accuracy, of course I reset them each day before starting any measurements.
Ole
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com
Idolenz
Joined: 13-Jul-2013
Posts: 6591
Posted: 18-Nov-2016, 12:49
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Posted: 18-Nov-2016, 12:49
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I meant the OP I am not so fond of quoting but in this instance it would have made sense ... Ole I know you are fan of minor details and so you have to be precise and consistent
tony.c
Joined: 27-Feb-2010
Posts: 772
Posted: 18-Nov-2016, 17:16
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Posted: 18-Nov-2016, 17:16
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Quote: "Sjoelund"Hi,
with these tools, I'm inside the 0.01 unit accuracy, of course I reset them each day before starting any measurements.
Ole
A digital caliper like that one is only accurate to about 0,06mm, if you want more precise measurements you need a micrometer, and be sure it's calibrated correctly...
World coins by date and mint place, 1850-2000
Sjoelund
Joined: 28-Mar-2012
Posts: 12379
Posted: 18-Nov-2016, 17:35
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Posted: 18-Nov-2016, 17:35
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A digital caliper like that one is only accurate to about 0,06mm, if you want more precise measurements you need a micrometer, and be sure it's calibrated correctly...
Hi Tony,
OK, it might be that the different calipers of this brand have that margin.... My measurements with THIS caliper might ALL be 0.03 (plus/minus=0.6) off, but I suppose it will be the same difference ALL the time?
This means that all my measurements of coin of the same type would be OK, since the mint's measurements are mostly given with more than 1 mm margin, which I suppose you can agree upon?
Ole
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com
tony.c
Joined: 27-Feb-2010
Posts: 772
Posted: 18-Nov-2016, 18:12
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Posted: 18-Nov-2016, 18:12
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Quote: "Sjoelund"A digital caliper like that one is only accurate to about 0,06mm, if you want more precise measurements you need a micrometer, and be sure it's calibrated correctly...
Hi Tony,
OK, it might be that the different calipers of this brand have that margin.... My measurements with THIS caliper might ALL be 0.03 (plus/minus=0.6) off, but I suppose it will be the same difference ALL the time?
This means that all my measurements of coin of the same type would be OK, since the mint's measurements are mostly given with more than 1 mm margin, which I suppose you can agree upon?
Ole
Hey Ole,
I don't want to start an argument, and we don't all own precision laboratory measuring equipment (surely that's not necessary for a hobby). I just wanted to say that there is always some tolerances on the given values. Even when measuring the same coin one might find small differences (not perfectly round, small edge damages...), but it will be close enough to determinate it .
Kind regards !
World coins by date and mint place, 1850-2000
Sjoelund
Joined: 28-Mar-2012
Posts: 12379
Posted: 18-Nov-2016, 18:25
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Posted: 18-Nov-2016, 18:25
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Hi Tony,
Ole
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com
glykan
Joined: 11-Sep-2013
Posts: 552
Posted: 20-Nov-2016, 13:19
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Posted: 20-Nov-2016, 13:19
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Having quite an experience (about 30 years
) of working with the precise laboratory balances, I can add my 2 cents to this discussion, which is: I wouldn't trust the claimed 0.01g accuracy of the (made in China) pocket electronic scales. And this is to put it mildly. I would more or less trust them within plus-minus 0.05g, but no more. And, please, don't think that their "inaccuracy" is consistent - it is not. It depends on the temperature in a room (and even 1 centigrade matters), humidity, battery depletion, vibration (how sturdy your table is), drafts, etc.
On a good side, you can keep your weight measurements in pretty good order if you can find a so called "weight standard" and calibrate your scale (some scale models have a "calibration" option) just before weighting off your coins. Ideally, the weight of the standard should be in a range of the weigh of your coin - let's say 1 g for small coin, 10g for the larger ones and 25-50g for big ones, since calibrating the balance in one range doesn't mean that you make them precise in the other ranges, usually it's quite opposite.
And I believe that much of this also applies to the electronic calipers, but a good micrometer would give you enough accuracy even for the precise measurement of the thickness of a coins.
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