500 mils.or mills One oz. Gold bars and Coins

This is a guide for those who wish to purchase a 500 mil., or 500 Mills gold bar or gold coin. First, consider is it actually gold. If the bar or coin is called a cetain mill thickness it is plated and not solid. Have any bar you purchase tested for purity, the acid test kits here on okay will answer that question. Most are marked .999 or nearly 24K, use the kit gepatible for 24K testing. Just scratch lightly! Second, If you buy a one oz bar , weight it too be sure, most seller are honest concerning this point! Third and the most important consideration, just how much gold content is there, in a 500 mills bar or coin?! Let's study a one oz 500 Mills bar, it is about 1/8 inch thick, now a "mil or mill" is one thousandth of an inch thickness, or in metric: 25.4 microns. Ok , by U.S. standards "Heavy Gold Plate" is at least 2.5 microns thick. Wow!,these bars must be ready heavily gold laden, since the gold on one surface of a 500 mills bar is 12,700 microns thick!,... yes on one side (500x25.4). So if we convert 12,700 microns to inches, we have 0.5 inch thickness on each side of a 1/8 inch thick bar! Is that math correct? Now here's where truth in advertising begees relevant. Why? The "500 mills" thickness should be expressed 0.500 mil in those auction titles, for a single side total of 12.5 microns or 5 times the legal minimun for heavy gold plate. Now thats not alot of gold , maybe a few dollars, so enjoy the 500 mills bar and coin as art or a collectible, BUT not an investment! Well, there is all that copper or brass under the gold plate!