Why are some coins more shiney than others?

[VAB2013]

I'm looking at 2016's, basically all uncirculated I would think. My dumb question is... although they are all shiney, every now and then I see one that is "super shiney" like a glass finish (I would say proof like) even though I have never seen a proof coin in hand. Why is this?

[willbrooks]

Shiney is a subjective term, so it depends on what you mean, but there are several things that will influence this.

Thing 1. Die state. Coins struck early in the die's life will generally have a more mirror-like surface, but as flow lines develop, the coin's luster gets a "cartwheel" effect.
Mint Luster: The reflective qualities of a newly struck coin. The flow of metal toward the rim from the striking process creates tiny radial flow lines that reflect light. As a lustrous coin is tilted under light, the reflected light will appear to move around the coin. This is called “Cartwheel Luster.” This cent below exhibits cartwheel mint luster. Photo donated by RLM’s Cents.


Thing 2: Die preparation: The preparation of the die and polishing can have a profound effect. Dies that are specially treated for proof coins produce a more mirror-like finish, even though they are created the same as business-strike dies.
Thing 3: Plating. The smoothness of the plating on plated coins varies from coin to coin, effecting the "shininess" of it.
Thing 4: Alloy: differences in the alloy mixture on older cents (or even impurities, like accidental zinc contamination in the plating) can also effect this.
Thing 5: Environmental exposure.
Thing 6: Probably other stuff too, lol.

[VAB2013]

Thank you very much Will for the detailed explanation. I have always wondered about this. Now I don't feel dumb for asking!

You know Will, I always save these pretty ones even when they are not a variety. I think that by the time my kids are old enough to have an interest in coins, the nice coins are going to be far and few between as far as what is circulated. So, when I am gone, my kids can look at these and think "wow, look at this" it will really be something to them then!

[jfines69]

Don't forget Thing 7... The mint hires lepricons to sit in the back room and polish planchets to a mirror finish prior to being struck

[willbrooks]

Don't forget Thing 7... The mint hires lepricons to sit in the back room and polish planchets to a mirror finish prior to being struck

Damn it, Jim, I thought that was supposed to be our little secret!!
Besides, that is exactly what I meant by #6: "Probably some other stuff too."

[jfines69]

Then what is 7???

[willbrooks]

Then what is 7???

Number 7 is: The perception of whether a surface is specular (mirror-like) or diffuse (reflecting or retaining, thus losing Mr. Shiney) is largely depended on the angle of incidence of the light and inversely proportional to the percent of eggnog in the bloodstream.

[VAB2013]

Thanks guys!! I needed a laugh today!!

[jfines69]

Number 7 is: The perception of whether a surface is specular (mirror-like) or diffuse (reflecting or retaining, thus losing Mr. Shiney) is largely depended on the angle of incidence of the light and inversely proportional to the percent of eggnog in the bloodstream.

UNCLE

[SuddenAdoration]

Hahaha ! Funny guys! And thanks for asking this question VAB2013 I was just wondering this myself.