So, theoretically we should be able to work out thickness ourselves if we know the weight and diameter and the density of the metal，because a coin is in a cylinder shape, and calculation is to work out the the volume 😂 . If the weight is known, then divide it by the density, we would know the volume. And then divide the volume by the area of coin’s face which is π x radius x radius, then we can get the height which is the thickness. 😂😂😂
However, it will not be 100% accurate though because a coin is not flat on surface, and also affected by number of decimal points chosen. So the result is more for indication purpose.
Most time if I need to find a coin’s thickness, I just google. Some dealers websites may have information for some coins, eg Sovereign’s dimensions can be easily obtained. However, need to bear in mind that thickness or diameter is not an exact fixed figure. It is a range.
Therefore, the best way to check if a coin is fake or not is to have it tested, and it is better to use non invasive methods, for example XRF (can work on directly on the metal to show its composition but not good at if the metal is in packaging), Sigma verifier (can work on the metal if it has thin packaging but can’t show composition and only limited to certain alloys or coins), Specific Gravity Test (cheapest method but need a bit time, and result may be affected by various factors in the process). Sometimes one method can’t give you a solid answer, so you still have to do cross check using a different method.