What do you think of my mint state grading diagram?

[Forest City]

I made this diagram for my writings in my Peruvian Dinero set, but I felt it had general application to all coin series so wanted to post it here.

Essentially, it shows the relation of luster on one axis. and contact on the other. to a coins grade.  The lower the grade, the more possible variability.  Whereas an MS 67 coin will almost always have full luster (possibly slightly subdued by toning) with only very minor non-focal contact, an MS 63 may have no contact but only decent luster, or it may have full blazing luster, but lots of (but not extreme) contact.  Or it may be inbetween these two extremes: having slightly above average luster, and moderate contact.

Yes, I realize that strike and eye appeal also play a roll; but it would seem these only move a coin up or down infrequently, and only after you take the big two: luster and contact into account.   

I'm curious for any comments.  If you like the diagram and find it helpful.  Or if you think I errored in my assessment of current standards, I'd love constructive criticism.  I hadn't seen a chart like this before, so I don't believe there is anything similar, but I could be wrong.

[physics-fan3.14]

I saw that diagram when I was perusing your set. 

I think it is an interesting idea. I agree that strike is less often used in grading (although it should be). Eye appeal, however, plays a much more significant role than you are estimating. 

When I grade a coin, I like to evaluate each of the 4 aspects separately. This coin has a strike of a 63, luster of a 66, eye appeal of a 65, and contact marks of a 62. (It might actually be easier to rank them on a scale of 1-5 or 1-10 like you have). Then, using each individual score, I figure out what the overall grade should be. I don't have a chart or a formula, its more of a gut feel. 

What I would really like to see, but I know will never happen, is for the TPGs to grade coins and put this information on the label. One single number (64!) can never tell you all the information about a coin. They do this with the ancients (strike and surface scores are broken out on a separate 1-5 scale, which I really like), but I'd like to see it for all coins. 

[Forest City]

Bill, your grading system reminds me of the old NCI grading by James Halperin, which is quantifiable.  

His system is:

Obverse: Rate Surface Preservation, Strike, Luster, and Eye-Appeal from 1 to 5.  Surface preservation is multiplied by 2.  Add them up.  

 

5-10.49 is 60

10.5 to 12.49 is 61

12.5 to 13.99 is 62

14 to 16.99 is 63

17 to 18.99 is 64

19 to 20.99 is 65

21 to 21.49 is 66

22.5 to 25 is 67 (that was the top grade at the time)

 

This system has some flaws.  I don't think strike should be given the same weight as luster for instance.  

I figure with eye-appeal, if you assign a grade to a coin on my chart, it may move up or down 1 point due to eye-appeal, but not more than 1 point either way.  Generally I find most coins can be explained by just the two variables luster and contact.

[physics-fan3.14]

My system is definitely based on old school grading. I agree that strike is less important, but it still needs to be considered. 

The reason I don't use that system is because the Formula you describe takes all the subtlety out of it. It is too rigid. It is a useful guide when learning to grade, but I can't just plug it into a formula and come up with a grade. 

[Ike2]

I totally agree that there needs to be more descriptive info included in the grading designation included in TPG labels.  If, as I understand it, TPG was introduced to allow "sight unseen" buying and selling of coins, the process no longer works very well.  The current sophistication and discrimination employed by most coin collectors and dealers to value a coin demands more detail.  For example, a regular old MS-XX Morgan dollar may bring $X at sale, but the example of the same grade which exhibits monster rainbow iridescent toning may bring $10X.  There should be some way of reflecting this difference in quality and desirability on the label.

I have long thought that a 1-to-5 (sorry, 1-to-10 is over doing it) numerical sequence could be added behind the grade to quantify strike, toning, and eye-appeal (I believe the TPGs already highly factor contact into their grade assessment, so I wouldn't include that).  The number 1 could describe the best strike, the least toning, and the most attractive eye appeal.  In the Morgan example above, the "regular old" coin might have a grade shown as MS-XX-313 (average strike, no toning, average eye appeal) while the monster version might be shown as MS-XX-351 (average strike, maximum toning, but huge eye appeal).

To be honest, even if this system were in place, I would NEVER buy a coin sight-unseen - not even a CAC'd one, but at least I'd have someone else's opinion about it.