Can Proof-like Coins still have Cartwheel Luster?

Or to put it a different way, where do you draw the line between Proof-like and a non-proof-like business strike coin?

Thanks in advance!

 

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Here's one example of mine that's PL-ish to which I'm referring to.

I see mirrored fields and light cameo devices, with a very strong cartwheel luster.

It's far more mirrored than any freshly struck MS coin.

Does it count as proof-like?

 

Absolutely NOT.

Long ago, collectors/dealers used the term "semi-prooflike" to describe coins which approached a mirror surface. That's what it appears you have here.
Semi-PL fell out of favor and is not used.

Best way to learn the difference between PL and DMPL is to look at graded coins; ask dealers or professional TPG's; or take a grading class. It all has to do with the depth of the "mirror" AND THERE IS NO SET STANDARD although you will read some. The rarity of the coin in PL also skews the standard.

 

I've looked at a ton, believe me you.

I thought it was "easy" for a while lol.

And then came the Canada PL vs Proof coins...

 

I use a Canadian collector to tell the difference. As I don't collect Canadian coins I don't care to know as it is above my pay grade.

 

OVERALL, this is an excellent explanation of luster. BUT (as is my usual habit) I should like to correct some things in the post.

Info here is close enough for government

 

Thanks for your detailed response, as always, GDJMSP.

I enjoy reading them. Will absorb.

And yeah, I go off on a tangent often. What I'm really asking is everything all at once lol.

 

My question to you all is, do all the world's Mints strike business coins that result in cartwheels when the dies aren't heavily polished? Is it the nature of how dies are made and/or how planchets are made, or their combination, which causes a cartwheel luster effect on the final finish? Or, is it the striking process?

 

I know it when I see it, too, but I like to see it as "% contrast" with the fields.

Wouldn't that be concretely measurable, especially when analyzed by computer software, while using the average human-eye-observed deep cameos and cameos as baseline examples? This more objective approach would assume subjective human examples as its basis, but for all intents and purposes, I think it'd be pretty close to getting it right.

 

Luster is created during the striking process (stamping). The metal actually becomes liquid (high temperature and pressure) and it's the flow lines of the liquid metal that create the luster when the coin hardens.

 

This comes up every time someone talks about "metal flow," but it's clearly wrong. Silver liquifies at 1,763°F / 961.8°C. There's no way a coining press is generating temperatures that high. What's going on is that the material's natural ductility allows it to flow when struck.

 

I'd like to expand your post to "It is the flow of the liquid planchet metal into the microscopic grooves worn into the die that create the raised radial lines that give the struck coin its cartwheel luster." That's because the planchet metal of Proofs also flows during striking; yet there is no cartwheel or radials seen on fresh proofs.

 

I've been a collector for over 30 years and this is the first time I've had luster really explained to me. I've even taken some of the ANA courses and never got it. Of course I know to look for the cartwheeling luster, but I never understood the mechanics of why.

 

Don't forget to read post#7 for another view. I cannot believe your ANA instructors did not use Doug's example on the chalk board. He makes it so simple.

 

So basically the metal stretches in the direction dictated by the coining press process, creating peaks and valleys or "mountains", which causes light to bounce off in a way to create a cartwheel luster effect.

And, a super enlarged, analogous example would be how some coins' designs with sun's rays create a cartwheel luster-like effect, right? Even wider separation (up to a certain point) of rays would still cause a cartwheel luster effect. This reminds of one such example as the 1924 Russian 1 Rouble coin below. There's absolutely no cartwheel luster remaining on the entire coin itself, yet the sun's rays cause a cartwheel luster to appear only in the area of the rays. If the sun's rays are stripped off, damaged, cleaned, what have you, then the cartwheel luster effect will disappear. Similarly, if coins are improperly cleaned or experience other types of damage, then these peaks and valleys become flattened or evened out. This is what goes on with fresh business strike coins, but on a much smaller scale, right?

 

What you describe in the sun rays is from a cleaning with a cloth or other rubbing medium. It leaves luster in the small spaces that it cannot access.

 

Will one of you Please take the time to answer this!

 

@iPen,
Please do this for yourself. Take the coin with the side you have in the photo over to an incandescent desk lamp. Turn the other lights in the room off. Now, hold your coin flat. Rock it back and forth while at the same time turning it with your wrist. This coin is loaded with luster and should have a propeller-like cartwheel that moves in a circular direction as you tip and rotate the coin at the same time. You should see it. Let me know.

 

You actually quoted me as I was editing my post, which is of course completely fair game
But anyhow, this coin retains luster in the small spaces and areas very close to the relief features. That is pretty evident in the pictures. This also fits with the OP description that the fields have lost luster but the sun rays have not. Classic rub-clean here.