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What are the allowed deviations of coin weight?


gxseries

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Coin weight is one of the hardest aspects of a coin to be counterfeited as there are various combinations of metal alloys, unless coins from the same period were melted down and then reused, which can be a possiblity.

 

But, what are the allowed deviations? I know that this varies specifically from what periods and what countries they were minted in. For example, for most modern coins, the allowed "error" range would be approximately 5%+- (most likely lower than this figure) off from the standard usual weight or +- 0.1 gram, which could be another example.

 

But can we apply this to coins that were minted in let's say around the 1800s? 1700s?

 

From what I read, there were some countries that were absolutely strict about their coin weight, as coins were mainly backed by the metal content. Does anyone know the range of such variances during such periods? And especially how if you minted over 10,000+ coins and making sure that almost all of them were under minted under strict weight conditions. :ninja:

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I don't think i can answer your question but i can confirm one of your points. Britain was fairly strict with the coin weights (obviously it varied from period to period) but at certain times in the 17th/18th century they were very particular about it. Hence why coins exist exhibiting adjustment marks where metal was scraped off of an overweight blank.

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I don't think i can answer your question but i can confirm one of your points. Britain was fairly strict with the coin weights (obviously it varied from period to period) but at certain times in the 17th/18th century they were very particular about it. Hence why coins exist exhibiting adjustment marks where metal was scraped off of an overweight blank.

 

The same situation holds true for United States issues. Before the advent of more precise manufacturing techniques, silver and gold coins in the early Federal period often exhibit adjustment marks to ensure the coins contained the precise amount of silver or gold required by law. Since the dollar was defined by Congress as a specific weight of silver in grains, it must have had incredibly tight tolerances (one grain in avoirdupois is equal to 0.002285 oz.). The original act defined a dollar as 416 grains (0.8667 troy oz. or 26.96g) total, or 371 4/16 grains of pure silver, while the eagle ($10) was 270 grains (0.5625 troy oz. or 17.5g), or 247 4/8 grains pure gold.

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I should also mention that since the beginning of the mint in 1792, all coins produced were required to be independently assayed by another office in the government (I forget which) to ensure they met the standards required by law. Also, there was in interesting article in Coin World this last week about contemporary counterfeits in the 1890s. Since silver bullion was so cheap (at the low, the value of the silver in a silver dollar was worth less than 50 cents) many counterfeiters were producing coins with greater fineness and more silver than the US Mint, and they were still making a profit!

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Hm... I have read that most countries were very strict when it came to such metals in modern mintage.

 

I mean, I still haven't come across any materials that discusses how mints used to check and control such massive mintage.

 

I am assuming that such coins were weighted in terms of thousands, but that will not single handly pick out coins that are overweight or underweighted...

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The same situation holds true for United States issues.  Before the advent of more precise manufacturing techniques, silver and gold coins in the early Federal period often exhibit adjustment marks to ensure the coins contained the precise amount of silver or gold required by law.  Since the dollar was defined by Congress as a specific weight of silver in grains, it must have had incredibly tight tolerances (one grain in avoirdupois is equal to 0.002285 oz.).  The original act defined a dollar as 416 grains (0.8667 troy oz. or 26.96g) total, or 371 4/16 grains of pure silver, while the eagle ($10) was 270 grains (0.5625 troy oz. or 17.5g), or 247 4/8 grains pure gold.

On quarters it was a few tenths of a gram. I discovered this when calibrating my specific gravity measurement device. All the coins were of good silver but there was a noticeable if not large variation.

 

I believe the exactness came more in bulk than in individual coins. Each $1000 worth of silver would have a very strict tolerance in percentage terms while an individual coin could have a little more leeway.

 

I have the numbers on my other machine, I'll post them tonight.

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Depends entirely on the coinage system in operation and upon how society accepts the cash.

 

Take early medieval England, prior to Henry II's recoinage in 1180 there is some deviation in the purity of the silver. The standard of the pre-1180 years was to get the silver as pure as it could be got, so that could range anywhere between .925 silver and .999 silver. Which is quite a difference. One pound's weight of silver (presumably troy) was coined into 240 pennies (hence why there became 240 pennies in the denomination £1).

 

The exchange system at the time was more of a barter system, people weighed the coins, if it was the right weight it was accepted. Obviously they must have accounted for slight variations in weight due to the variations within the silver purity, but then again the weighing implements of the time were nowhere as near as fine tuned as they are now. But if the penny weighed 1/240th of a pound then it was good.

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Of course by the late 18th/19th centuries coins were still accepted by weight but more increasingly as the 19th century progressed if it was the right size and the right design it was accepted even if the weight varied. Whereas centuries previously it didn't matter what the design was or what it looked like, if it was silver it was acceptable, the amount it traded for depended upon how much silver was there.

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Hm... I have read that most countries were very strict when it came to such metals in modern mintage.

 

I mean, I still haven't come across any materials that discusses how mints used to check and control such massive mintage.

 

I am assuming that such coins were weighted in terms of thousands, but that will not single handly pick out coins that are overweight or underweighted...

 

 

They used coin weights and weighed each coin individually. They had a different wieght for each denomination. The weight would go on one side of a balance scale and the planchet on the other. Too light and it was rejected, back into the melting pile. Too heavy and the adjustment tool came out - a scrape or two and all was well and off it went to the press.

 

Today many collect these weights - yep they're still around. And can be found for most denominations and for most countries - some are harder to find than others of course.

 

A quick Google search for "coin weight" will show many examples.

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O.K When I measured some Washington Quatrers from an XF-BU roll I got these results

 

Coin # Avg Wt (g) Avg Wet Wt (g) SG

1 6.283 0.61 10.3

2 6.17 0.607 10.2

3 6.193 0.593 10.4

4 6.123 0.597 10.3

5 6.247 0.62 10.1

6 6.203 0.617 10.1

7 6.143 0.597 10.3

8 6.21 0.603 10.3

9 6.147 0.597 10.3

10 6.09 0.587 10.4

11 6.177 0.6 10.3

12 6.087 0.6 10.1

13 6.37 0.627 10.2

14 6.237 0.61 10.2

15 6.16 0.6 10.3

16 6.217 0.61 10.2

17 6.19 0.597 10.4

18 6.14 0.603 10.2

19 6.2 0.603 10.3

20 6.107 0.597 10.2

21 6.13 0.6 10.2

22 6.097 0.593 10.3

23 6.303 0.62 10.2

24 6.297 0.613 10.3

25 6.27 0.607 10.3

26 6.302 0.617 10.2

27 6.267 0.607 10.3

28 6.137 0.602 10.2

29 6.117 0.6 10.2

30 6.183 0.6 10.3

Avg 6.193233333 0.604466667 10.24658135

 

My set up does have some margin of error but I think it's save to say that for single coins +- .1 grams (stated weight is 6.25) is quite normal for 1932-1964 silver US quarters.

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Some of that variation can be accounted for by the wear on the coins as that would reduce their weight. Also, I am not sure how strict the mint was on modern silver (i.e. 20th century) since these were produced in such large quantities by more precise manufacturing methods. I do know that gold coins were meticulously assayed to ensure thay each coin was produced to the exact weight and fineness required by law. At least up until 1933 that is!

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Yes jlueke but i did cover why modern coins can vary so much in a post earlier. Other than vending machines (and not all of them) how many people these days weigh coins to see if they are the acceptable weight? How many people in 1900 had a pair of balance scales setup to ensure they weren't being cheated out of a few grains of silver.

 

In modern times people accept coins on their size, what they look like and what they say on them. So the mint no longer has to be precise about it. That an since most coins are now made out of base metals there's no point anyhow. Although i still find it amusing how some countries (probably the UK and the US but i'd have to check) have retained the practice of weighting the coins in relation to one another. E.g a 10p coin would weight twice that of a 5p coin.

 

This shouldn't be so surprising with the US series because the coins just switched metal and the sizes and design remained the same. The UK change all the metals way back in 47 and then changed all the sizes many years later, but yet the old relations between the coins remain. As does the edge milling.

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Your are correct, I am just demonstrating some evidence that silver coins varied by measurable amounts since at least the 1930's. For clad coinage the exact weight is pretty irrelevant except that over billions of coins that scrap metal costs probably add up.

 

I think the tolerances were much tighter on the big bags of coins released (in % terms) compared to teh individual coins.

 

Personal weighing of coins probably lasted well into the 19th centuries in many if not all countries that used precious metal coins.

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I don't know the standards used in other countries, but I have a list of the allowed tolerance for most US coins.

 

Small cent 1856 - 1971 was 2 grains or +/- .13 grams

Small cent 1972 - 1982 was 1.9 grains +/- .12 grams

nickels 1855 - date 3 grains +/- .19 grams

dimes 1.5 grains +/- .09 grams

 

quarters 3 grains +/- .19 grames (notice it is geting stricter. Weight of coin up 2.5 times, tolerance up only 2 times)

 

Halves 4 grains +/- .26 grams (weight up 100% tolerance up 33%)

 

silver dollar 6 grains +/- .39 grams (weight up 100% tolerance up 50% compared to the dime the weight is up ten times, tolerance up four times.)

 

Ike dollar 40% or clad 8 grains +/- .52 grams This is the only clad coin not held to the same standard as the silver versions.

 

Gold coins were held to much stricter tolerances especially as the weight increased.

 

gold dollar .25 grains +/- .02 grams

 

quarter eagle .25 grains +/- .02 grams weight up 150% tolerance up 0%

 

three dollar .25 grains +/- .02 grams still 0% increase in tolerance

 

half eagle .25 grains +/- .02 grams still 0% increase in tolerance

 

eagle .5 grains +/- .04 grains ten times the weight of the gold dollar with only a doubling of the tolerance allowance.

 

Double eagles .5 grains +/- .04 grams Weight doubled again with no increase in tolerance.

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I don't know the standards used in other countries, but I have a list of the allowed tolerance for most US coins.

 

Cool, do these come from the mint?

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My god, that's really some excellent infomation there Conder101. Thanks!!!

 

Still I don't understand how such deviations are being kept. I mean, if you are minting over thousands per day and trying to make sure all of them are in proper conditions, how is still possible when digital technologies weren't really available?

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The information came from the Coin World Almanac 1976 edition. Some of the other editions have even more complete listings of the tolerance tables. That just happed to be the first one I grabbed.

 

It is amazing the amount of information that can be found in the Coin World Almanacs. If I have any general numismatic question that is usually one of the first books I consult. I use them so frequently that I have a complete set of all five editions with back up copies of the first four editions. (The 2000 millennium edition is something of a disappointment. It has a lot of infomation but it isn't as good as the previous four.) I use all of them because each edition has some information that isn't in the others.

 

As for how they managed to do the weighing, in the early mint they were not striking thousands of coins a day, and the mint had in it's employment a group of women whose job it was to weigh each planchet. Light ones were condemned, normal one passed, and heavy one were passed over once or twice with a file to reduce the weight and weighed again until the did pass. The weomen wore leather aprons so the the silver or gold filings did not stick to their clothing and at the end of the day the aprons and collected filings would be turned over to the melter for recovery.

 

Later as equipment improved the weighing of the blanks was eventually done by machine. It wouldn't be difficult. Think about an open link chain traveling down a track with two counterweighted traps in the track. A planchet is slid forward inside each link. As it passes over the first trap if it weighs more than the maximum allowed for a normal planchet the trap tips down and the planchet drops into the heavy bin. Otherwise it continues to the second trap. Here if it weighs more than the MINUMUM legal weight for the coin it tips down and drops into the legal weight bin. Anything that gets past both is light weight and goes back for remelting. A machine running at one coin per second like this could easily weigh 3,600 planchets per hour. (And I believe it could probably run up to ten times as fast, or 36,000 planchets per hour.)

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It looks like I will need to find myself a Coin World Alamanac, preferably not the millenium edition. I see a few for $35 and then a bunch for $5-$10. Must be paperback versus hardcopy.

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If you are a subscriber to Coin World you can register on the Amos Advantage website. Then do a search for Coin World Almanac. You are looking for product number CNW09. It is the hardbound copy of the 1995 edition. It lists for $20, but for registered Amos Advanatage members it's $5. With shipping something like $8. (That's where I got my copies.)

 

If you aren't a Coin World subscriber let me know and I'll see about picking up a copy for you.

 

The direct link to it is 1995 Coin World Almanac

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Thanks for the offer.

 

:ninja:

 

I'm not a CW subscriber but I do see a few on bookfinder.com so I will order one there.

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You can find the tolerances for just about any nations coinage in specialty books - as usual, books are the key to knowledge in this hobby. It should also be noted that weight tolerances as well as purity tolerances quite often changed over time.

 

The following are tolerances for columnarios and Spanish American silver coins 1728 - 1825.

 

8 reales - max 27.2638 gm - min 26.8646 gm

4 reales - max 13.6818 gm - min 13.3824 gm

2 reales - max 6.8658 gm - min 6.6662 gm

1 reale - max 3.4828 gm - min 3.2832 gm

1/2 reale - max 1.7414 gm - min 1.6416 gm

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