In the minting process, what makes one coin more lustrous than another?

1907Quarter

die polishing, the number of times between polishings? Does die polishing effect the strength of the strike?

stujoe

Check out the explanation about lustre half way down on this site. It is kind of interesting.

B. The Meaning Of Mint Luster

koynekwest

Die polish can eliminate the shallow elements of the design-in extreme cases-the leg on the 1937-D Buffalo
nickel-is a prime example. It can also intensify lustre. Early die state coins will usually show a smooth satiny lustre with sharp lettering and crisp design elements. Flow lines indicate a later die state and are radial in nature-from the center of the coin toward the rim, especially noticeable near the rim. These can also show intense lustre, but much of the lettering will be indistict where it joins the field. EDS (early die state) coins
are always the most desirable both on regular issues and, especially, on doubled dies.

koynekwest

One other thing I've noticed-moderate die polish seems to allow for a better strike on higher relief coins, such as Buffalo nickels (my specialty) since it microscopically reduces the depth of the field to the deepest parts of the design-often enough to allow for a full strike.

lordmarcovan

Die polishing probably has its effect. But luster is really caused by flow lines in the metal of the planchet itself.

lathmach

Lordmarcovan is correct. You get luster from the flow lines. Therefore a well used die will strike coins with much luster while a new die will strike coins that are prooflike.

Ray

Conder101

True but the flow lines are a result of the planchet metal moving along the surface of the the die so the smoothness of the die is important. If the fields of the die are very smooth as on a new die or freshly polished die you get a prooflike coin and they usually don't have a lot of luster. As the fields just start to wear you begin getting very fine radial flow lines and the cartwheel luster starts to come out. As the fields of the die wear the cartwheel becomes stronger up to a point and then it starts to braoden and weaken as the fields become worn enough that the flowlines start becoming larger. Eventually flowlines start forming on the die faces and the coin surfaces start to take on an "orange peel" appearance. If it continues the dies can start crmbling and the lettering and/or details on the coin start looking smeared or doubled. Once the "orange peel" starts the luster is gone because the light is no longer reflected from the coin in a particular direction but instead is scattered by the irregular surface.

cladking

Planchet quality is a primary determinant of luster. A very clean planchet will
produce a slightly better looking coin than a poor planchet with lots of scratches.
But, a polished or partially polished planchet can make a superior example. Get
examples of your favorite coins struck off-center so you can see this before and
after effect.

Many factors enter into luster: die condition, planchet annealing, temperature,
planchet smoothness, toning/ corrosion, striking pressure are the major ones.