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<p>[QUOTE=&quot;lilbyrdie, post: 840518, member: 24183&quot;]Hello,</p><p><br /></p><p>I&#039;ve checked a few threads on scale accuracy, but can&#039;t find a whole lot of specifics on this. </p><p><br /></p><p>I recently got a scale that claims 0.01g accuracy. I figured a low-cost scale claiming that accuracy should, at least, be slightly better than a 0.1g accuracy scale. So, to test, I took a pile of the 2010 Native American $1 coins (via the direct ship program from the US mint). The US mint lists these coins as being 8.1 grams each.&nbsp; Yet, on this shiny new scale, 10 of them weight 80.0x grams (x changes a little based on which ten). A single one almost always weights in at 8.01g. To compare, I took one of our food scales -- accurate to, at best, 0.1g -- and weighed 10 and 20 coins. Still, it comes out to 8.0 grams each, not the expected 8.1g.</p><p><br /></p><p>20 nickels typically comes out at around 99.98 grams on the &quot;better&quot; scale and 100 even on the food scale. This is far closer to what I&#039;d expected as far as accuracy and tolerance goes.</p><p><br /></p><p>8.0 grams vs 8.1 grams is a difference of just 1.2%, but I don&#039;t seem to have any examples that are different and the readings are consistent regardless of the number of coins or which coins. I would have expected that coins to be a range, but average to the listed weight. </p><p><br /></p><p>1. The source of the weight specification I&#039;m getting is from the US mint (<a href="http://usmint.gov/about_the_mint/?action=coin_specifications" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://usmint.gov/about_the_mint/?action=coin_specifications" rel="nofollow">http://usmint.gov/about_the_mint/?action=coin_specifications</a>) and other sites say the same. However, none of them list acceptable tolerance or variance. Where do I find this information? How about for old coins and world coins?</p><p><br /></p><p>2. If I&#039;m weighing for a first pass at authenticity testing, what accuracy should I be looking for? I&#039;d assumed more than +/- 0.05g off would be an obvious indicator, since most coins are published to at least thousandths of a gram accuracy or more, and any fake trying to be really tricky would hit the numbers precisely. But, the dollars from the mint are even farther off... If a couple tenths of a gram variance is expected, then I can see why most people use 0.1g scales. But, then, I also don&#039;t see the point in publishing numbers of such higher accuracy, such as 2.2268g for a dime, especially if it could actually weigh 2.3 or 2.1g (and, besides, the loss of getting a few fakes would, for most people, be less than the cost of a scale that can accurately read to 0.0001g).</p><p><br /></p><p>3. How can a calibration weight be trusted any better than the scale itself?</p><p><br /></p><p>Thanks for any helpful info and insight![/QUOTE]</p><p><br /></p>

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