There is a reasonable amount of information available on how to grade a stamp regardless whether one agrees with the information or not.. However, if you are a cover collector there seems to be precious little. I submit that the following can be used as a guide on how to grade a cover.
For each of the following points I assign a numerical value from one to ten, where one is extremely poor quality and ten is perfection.
Point 1) What is the condition of the cover? Is it torn or not; extraneous information written-upon it or not; or have a piece missing or whole? Does it have a stain or not; has it been folded or creased or not? All of these points would require a very low score.
Point 2) What is the size of the cover? Is it a standard personal size or an unusual size? Less desirable sizes are business, odd-shaped, and extremely large. In the U.S. an European size is considered less desirable generally. However, if you collect non-U.S. covers it should not be considered so.
Point 3) What is the condition of the stamps on the cover? Are they torn, have a piece missing or poorly centered?
Point 4) What is the condition of the postal markings? Are the faint, missing sections or smudged or are they clear, sharp and complete? Are all of the markings on one side of the envelope or both sides? Does it have all common postal markings or are there unusual ones? Note: Each postal marking must be judged separately and then the total points given are to be divided by the number of markings.
Here is an example of a cover that I have rated and my reason why I gave it the rating I did.
The cover is clean, whole and stain free but shows some signs of being rumbled at bottom left. Therefore I assign it 8 points.
It is a U.S. standard sized envelope. So, it receives 10 points.
Being a postal stationery items it has no added adhesive stamps. Therefore, the points made are not applicable.
There are 2 postal markings and 2 private markings. Looking at each I would make the following rating:
Santa Ana marking – very clear, very sharp and 95% complete - 9.5 points
San Salvador “cogwheel” – very clear, very sharp and complete - 10 points
Via Panama & New York – clear, somewhat faint & complete - 8 points
Merchant marking – clear, sharp and complete - 9 points
There are 3 postal markings and one merchant marking on the reverse
2 Mannheim markings – very clear, very sharp and complete - 10 points each
Santa Ana marking in blue (between Mannheim markings) - clear, rather faint and complete - 7.5 points
Clear, sharp and complete - 8 points
The total points for all markings – 72 points. Divided by number of markings – 9 points.
Thus, I would rate the cover with a total of 27 points, which I divide by 3 as the number of applicable points for a score of 9. Out of a possible score of 10 I would have to rate this as Extremely Fine.
What are your comments?