(Meta)Philosophy of RD, RB, & BN Designation - The Role of Cu, Ni, & Other Elements

I noticed that the Flying Eagle Cent doesn't come with a color designation. My guess is that it's because of the FE's nickel content (88% Cu, 12% Ni), but also because of the non-red mint state color I've been seeing a lot of in slabs. So, it looks like unless it's pure copper, bronze (Cu & Sn), or brass (must have at least Cu & Zn), then coins won't receive any color designation. Obviously if you add other elements such as tin to brass to create a different alloy, then that has been allowed (cartridge case cent).

However, what if it's say, 99% copper and 1% nickel? If that's not given a color designation, then is it then the addition of nickel that prevents the color designation even if the color is red when struck? If that's true, then a brass coin with say, a 1% Ni content would not be given a color designation either (e.g. if the Flying Eagle cent were to be 99% Cu & 1% Ni, or for that matter, any % Ni content below 12%). So, is nickel and certain other elements the true culprit in denying copper and copper alloys its color designation? Another example are the Sacagawea dollars which have a composition of Cu 88.5%, Zn 6%, Mn 3.5%, Ni 2%.


Is this why modern nickels, dimes, quarters, etc. with missing clad layers, wherein the nickel layer is missing (even when both sides are missing and only the copper remains), is not assigned a color - because there could be a trace amount of nickel there?

Thanks in advance!

 

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I guess that was a very loaded question lol.

 

Alloys can make color quite interesting. Take for instance this:



This is a UNC Korean 1 fun coin struck in 95% copper and 5% aluminum. Regardless of how high the copper content is, the small percentage of aluminum makes it look like it's struck in brass.