Undersized Platinum Proof?

supercoin

I've got a 2002 $100 Platinum Proof that is slightly undersized in diameter... it rattles within it's plastic capsule. I originally thought it was the case but after swapping cases with another coin it's the same issue. I think I have a micrometer somewhere and will try to get exact measurements.

I'm wondering if anyone has an explanation for this? Do the collar dies vary in size that much?

And of course most importantly... am I rich?

clevegreg

I think you got one of the special .9 Oz. coins that the Mint is making to help with the budget deficit

Greg

TheNumish

Had some uncirculated 1 oz plat eagles once where the rims were railroad rims and the coin was different thicknesses all around the edges. Sent them to Fred Weinberg and he told me they weren't worth anything extra. I think since plaitinum is so hard to strike it's not unusual for the coins to be like this. Of course a proof might be a whole different situation.

Have you tried weighing the coin?

supercoin

Hmm... interesting theory clevegreg.

Here are the measurements, bearing in mind that it's tricky to measure diameter with a micrometer...

Rattling coin: 1.2825
Another coin I measured: 1.287
US Mint specification: 1.287

So it's .0045 inches too small. Not terribly dramatic to the naked eye , but enough to make it rattle in its case.

supercoin

TheNumish, I haven't tried weighing them, all I have handy is a postal scale accurate to only 0.1 oz.

Both the rattling and non-rattling coin appear to be well-struck, i.e. the reeding is fully struck-up, as best I can tell by just looking at them. So that doesn't appear to be causing the diameter difference.

I noticed the non-rattling coin has a partial finned rim, so the extra thickness might also be part of what's keeping it from rattling.

supercoin

Scratch that last thought about the finned rim... the undersized coin rattles, and the normal sized one doesn't, even before the capsule is closed. So, it's the diameter.

The finned rim, might, however indicate a more fully-struck coin, especially around the circumference, since it was struck hard enough to force some of the metal through the seam around the dies.

If I recall correctly, the 1oz platinum proofs are struck nine times.

Gilbert

Hey SUPErcoin,

Do you know what the acceptable variations are for this specimen?

I wonder if Weinberg's opinion is based on the fact it is bullion vice a circulating coin. I suppose weight and fineness are more significant; although, it seems some aspect of the detail(s) would be lacking with striking pressure insufficient to completely fill the collar. How else could this occur ; an undersized collar? In that case, I imagine it would be an interesting variety of "error". Something to consider anyway.

supercoin

Nope, I don't have a clue as to what the acceptable variations are.

It is the first one I recall handling that rattles, out of maybe 100 I've handled (of all years) but that's about all I know. Judging from the lack of people offering to buy it for huge money, I'd guess there's little demand.

Actually I'm torn as to what to do with it, it's the nicest 2002 I've come across (bad year for them, apparently) but I plan on keeping it in the gov't packaging and frankly the rattle bugs me.

Conder101

Five thousandths of an inch is probably pretty close to the mints tolerance before they would reject a collar as being too worn but that would be five thousandths of an inch LARGER than the prescribed size not smaller. I can't see how you could have a fully struck undersized coin. Is the edge well struck and squared off as well? If it is that would seem to imply an undersized collar. But that would create a problem as well. Most likely the dies wouldn't fit into the smaller collar. The dies would be constantly banging into the collar with every strike. And how would an undersized collar be created?

keets

tad

mic the undersized coin diameter in 3-4 different places and let us know what the variance is.

al h.

supercoin

I just checked it again, and it definitely appears to be fully struck. The rims are "square", with even a hint of finning present.

One new thought, maybe the recesses in the collar that form the reeding became clogged with some platinum, and so the reeding on my coin is not as peaked as it should be?

That would assume the platinum residue would accumulate in the collar, rather than sticking to newly struck coins, which I'm not sure is a valid assumption.

Or maybe a grease-filled collar?

supercoin

keets, measuring every 45 degrees (working fairly quickly) it varied from 1.2820 to 1.2827.

If there's some old-timer machinist's trick for quickly and accurately measuring diameter at the widest point, I can try again.

I don't want to mess with it too much, just a matter of time before I drop the micrometer on it or something.

MadMarty

Send a PM to Kincoin, maybe he will give you $25,000 for it... Then he can put it on E-Bay for $250,000

supercoin

You mean after I drop the micrometer on it?

supercoin

One last try for an overwhelming wave of enthusiasm for this coin... Anyone think it's worth saving? Don't really want to have $750 tied up for a mild novelty.

KINCOIN

supercoin
Expert Collector

You have measured the OD of the coin. Have you measured the thickness? It could also be a tapered planchet.

KINGCOIN KING OF COINS

supercoin

I haven't tried to measured the thickness... it wouldn't do much good to measure the rims since they vary so much with finning, and I really don't want to clamp my hardened steel micrometer onto the fields. I'm sure there are some fancy non-marring measuring devices, but I don't have one.

Anyway, I guess as with all errors (if that's what this is), the more dramatic the better... and this one isn't, unless you're a gnat.

Lacking any more input, I'm going to call it a grease-filled collar and forget it.