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<p>[QUOTE=&quot;Conder101, post: 842693, member: 66&quot;]Find a copy of the Coin World Almanac, specifications and weight tolerances for all US coins including the older ones.&nbsp; World coins are a little more difficult.&nbsp; The Krause Standard Catalog is pretty good for the silver and gold coins (no tolerances though) but somewhat hit or miss fo the base metal coins.</p><p><br /></p><p>Tolerance of the small dollars in 8.1 grams +/- .3 grams so almost a 4% variance.</p><p><br /></p><p><br /></p><p>I would go with a minimum of .1 gram accuracy.&nbsp; The tolerance of most US coins is less than +/- .2 grams.&nbsp; A scale that only reads in full grams is not accurate enough to detect&nbsp; out of tolerance fakes unless they are WAY off.&nbsp; For example the a Morgan dollar is listed at 26.73 grams with a .097 gram tolerance.&nbsp; A scale accurate to 1 gram would show it as 27 grams.&nbsp; A genuine coin would show 27 grams as long as it was in tolerance (26.6 to 26.8) but a fake has a much wider target.&nbsp; It would show 27 grams as long as it is from 26.5 to 27.49 grams.&nbsp; With a .1 gram scale the counterfeit has to pretty much hit that same weight and tolerance as the genuine coin.</p><p><br /></p><p>For first pass weighing a .01 scale is probably a little over kill.&nbsp; Where accuracy of that extent is needed is if you are wanting to run specific gravity tests.&nbsp; The differences between dry and wet weights are often less than a couple tenths of a gram and specific gravities have to be carried to at least one decimal place and preferably two places.&nbsp; If you want those figures to be accurate you need to have more precision in your weights.&nbsp; You aren&#039;t going to get that with a 1 gram or .1 gram scale.</p><p><br /></p><p>The good news is .01 scales are now readily available and pretty cheap.&nbsp; I have seen them at times under $20, about the same as the .1 gram scales.&nbsp; If you want even higher precision then they get more costly.&nbsp; (If you don&#039;t mind the slower speed and larger size of the manual scales sometimes you can get great precision cheap.&nbsp; I picked up a Becker analytical balance accurate to .0001 grams for $50 on eBay.&nbsp; An electronic balance that accurate will typically set you back a couple thousand or more.) </p><p><br /></p><p><br /></p><p>A true CALIBRATION weight is typically certified to be&nbsp; that weight and have been adjusted to be balanced to several decimal places in comparison to a standard weight from the National Bureau of Standards.&nbsp; (A NBS standard weight has likewise been adjusted to match, to even more decimal places, the Offical Standard weight.)&nbsp; Most &quot;calibration&quot; weights are not true calibration weights but are probably accurate for their marked weight to at least two decimal places[/QUOTE]</p><p><br /></p>

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