How do you gage the luster on your coins?

[Buffalo Head]

I love to image coins and if they're colorful and lustrous well struck pieces I enjoy it even more.

I have talked to folks who are professionals at grading coins and they'll tell ya that luster rules the roost when it comes right down to it. So, I was wondering how this is done? Do they use a gage? I know as a machinist when the finish on a work piece is important we will use a "finish gage" to compare. Now when imaging my coins I've noticed that when using a light meter the very lustrous coins I will have to adjust my shutter speed quicker and for coin not so lustrous I will slow this shutter speed down. I was just wondering if the pros. use some kind of light meter or is it just a meter in their head? Just a thought.....

[lcoopie]

I think that's where experience comes in seeing coins of multiple grades.

Each grade has an associated luster to it.

 

When I look over my coins and see a 64 It looks lustrous until I compare it to a higher grade.

[bsshog40]

I look for a nice flowing cartwheel luster, looking for any breaks as I rotate the coin.

[Dcoin]

When discussing luster, I think the light source is an important factor.

 

I can count several occasions, buying a coin and then looking at it in the car and thinking..."Wow the luster in there looked sooo much better."

 

Also for many pieces the difference between higher grades rests squarely on the level of luster.

 

[Buffalo Head]

When discussing luster, I think the light source is an important factor.

 

I can count several occasions, buying a coin and then looking at it in the car and thinking..."Wow the luster in there looked so much better."

 

Also for many pieces the difference between higher grades rests squarely on the level of luster.

 

I agree 100% on that statement, the luster on a coin is very important in the higher levels, no question.

Another good question is light source, as long as your looking at, or imaging your coins the same light, you'll never know the real difference.

I just noticed when imaging, the sometimes extreme difference in the shutter speed and what my light meter is telling me under the exact same light with two dirrerent raw coins, this can't be done with coins in plastic. And I also thought to myself, what a great way to judge the luster using a tool.

[Frank Provasek]

The cartwheel luster that most collectors like is actually caused by die deterioration. Fresh dies produce coins with a satin finish. And coins from dies that are refinished to removed the "cartwheel" radial lines either show die polish lines or sometime prooflike surfaces, depending on how they are refinished. Furthermore,

unless the mint worker wants to replace lots of broken dies, the die spacing is

adjusted to where the vast majority of coins will NOT QUITE be fully struck. And there won't be any mint luster on the high points if the dies never contacted the

metal, nor will the many nicks and scratches on the blanks (from tumbling and annealing) be flattened out. This all looks like WEAR to those unfamiliar with

the minting procedures. MANY grading books over the years told the collector to

look for "a trace of wear on the high points" to determine if a coin is Mint State or

not. A grey look in the open FIELDS is a far more accurate indication of wear.

 

So in simple words --- it's complicated.

[Walkerfan]

Good cartwheel effect in the fields (obv., usually) where there is alot of smooth surface area. In the light it looks like an oval shaped glimmer.

[Buffalo Head]

The cartwheel luster that most collectors like is actually caused by die deterioration. Fresh dies produce coins with a satin finish. And coins from dies that are refinished to removed the "cartwheel" radial lines either show die polish lines or sometime prooflike surfaces, depending on how they are refinished. Furthermore,

unless the mint worker wants to replace lots of broken dies, the die spacing is

adjusted to where the vast majority of coins will NOT QUITE be fully struck. And there won't be any mint luster on the high points if the dies never contacted the

metal, nor will the many nicks and scratches on the blanks (from tumbling and annealing) be flattened out. This all looks like WEAR to those unfamiliar with

the minting procedures. MANY grading books over the years told the collector to

look for "a trace of wear on the high points" to determine if a coin is Mint State or

not. A grey look in the open FIELDS is a far more accurate indication of wear.

 

So in simple words --- it's complicated.

 

I think your right on the money. It is complicated I suppose to a degree. The point you make with the die polishing is a great one ! I love the look of a well struck coin with heavy die polishing lines as it will bend the light for a "luster bomb" effect, I love that look on any alloy. Grading is an interesting subject that a guy can't learn enough about.

[Dcoin]

Buffalo- It does not surprise me that a head-strong buffalo nickel collector would note the differences between types of luster.

 

I've felt for a long time that the idea of luster as a defining factor in a coin shows up most notably in buffalo nickles. Maybe it's just that I'm partial to the series but booming luster can take a nickel from a 66 to a 67. I'm not sure the same can be said about many other series.

[cpm9ball]

The cartwheel luster that most collectors like is actually caused by die deterioration. Fresh dies produce coins with a satin finish. And coins from dies that are refinished to removed the "cartwheel" radial lines either show die polish lines or sometime prooflike surfaces, depending on how they are refinished. Furthermore,

unless the mint worker wants to replace lots of broken dies, the die spacing is

adjusted to where the vast majority of coins will NOT QUITE be fully struck. And there won't be any mint luster on the high points if the dies never contacted the

metal, nor will the many nicks and scratches on the blanks (from tumbling and annealing) be flattened out. This all looks like WEAR to those unfamiliar with

the minting procedures. MANY grading books over the years told the collector to

look for "a trace of wear on the high points" to determine if a coin is Mint State or

not. A grey look in the open FIELDS is a far more accurate indication of wear.

 

So in simple words --- it's complicated.

 

Okay, I want to try to complicate it a little more because easy stuff is no fun.

 

Frank, what role, if any, does metal flow play in all of this? I know when you look at a coin like a Morgan under a microscope, you can see how the metal flows in streaks outward from the center of the coin. How is the satin finish imparted by a fresh die affected (or enhanced?) by the metal flow?

 

Thanks,

 

Chris

[comicdonna]

Buffalo- It does not surprise me that a head-strong buffalo nickel collector would note the differences between types of luster.

 

I've felt for a long time that the idea of luster as a defining factor in a coin shows up most notably in buffalo nickles. Maybe it's just that I'm partial to the series but booming luster can take a nickel from a 66 to a 67. I'm not sure the same can be said about many other series.

Being fairly new to coin collecting, I can say that it was hard for me to spot luster. When Joe first started posting images of his georgeous Buffs, I was able to spot true luster of a coin for the first time.

[lcoopie]

That's a good explanation Frank

[Frank Provasek]

Okay, I want to try to complicate it a little more because easy stuff is no fun.

 

Frank, what role, if any, does metal flow play in all of this? I know when you look at a coin like a Morgan under a microscope, you can see how the metal flows in streaks outward from the center of the coin. How is the satin finish imparted by a fresh die affected (or enhanced?) by the metal flow?

 

Thanks,

 

Chris

 

You're on..

 

As the planchet is struck, the diameter spreads out...enough to make the reeded edges on the coins that have them, so it's a fair amount of spread. When the dies have become rough from use, that roughness plus the pressure from the strike causes friction and carves the cartwheel flow lines into the coin. Those pretty cartwheels are undesirable, because the friction makes heat, and also makes the coin harder to strike. Any factory (which the mint is) that makes die struck products wants smooth dies and a smooth finish on the product.