This article is from the Paper Money Collecting FAQ, by Bruce Giese firstname.lastname@example.org with numerous contributions by others.
The condition of a note is critical to its value. Lowering the
grade of a note one notch can decrease its value by 1/3 or even
1/2. An expensive note which falls between two categories might
be worth a thousand dollars more in the higher category than the
lower one. Thus, it's often important to be more precise than
using a limited number of categories.
But here's a general guideline. Note that many dealers have
slightly different grading systems, especially with various
sub-grades of uncirculated. There's no official system of grading,
unfortunately. But these are pretty much universally accepted.
I've received a lot of input and tried to hammer out the best
descriptions for each category.
Crisp Uncirculated, UNC or CU: This means absolutely not the
slightest sign of any handling or wear or folding or *anything*.
Some people use additional grades to distinguish qualities such
as perfect centering or other printing characteristics. Certainly
a note which has centering problems which are visible from a
distance of 1 meter (3 feet) should have this mentioned in the
Almost Uncirculated (or About Uncirculated), AU: This means there
is a slightly detectable imperfection such as a counting fold on one
corner or slightest fold in the center (nothing which breaks the
surface of the paper) or a pinhole. At first glance it looks like
an UNC note.
Extremely Fine, EF or XF: Generally three light folds or one strong
fold which breaks the surface. There may be slight rounding at the
Very Fine, VF: May have several folds although the note is still
crisp and has a minimum of dirt. There may be minor tears or very
small holes but nothing which distracts from the overall appearance
of the note. Take an uncirculated note and crumple it once in your
hand, then flatten it out: this is a Very Fine note. Repeat the
crumpling and it's still pretty much a VF note.
Fine, F: A circulated note where individual folds and creases may
no longer be visible. To distinguish this from a VF note, when
inspecting a Fine note, it clearly does not look like a note which
has merely been crumpled a few times: It doesn't have the crispness
and brightness of a VF note. No tears may extend into the printing.
This is your average in-the-wallet note.
Very Good, VG: Tears and small holes can be present. The note is
not crisp at all. The is your lower quality in-the-wallet note.
Lots of people on the 'net don't realize that a note in "very good"
condition is really pretty lousy.
Good, G: Small pieces missing, graffiti. A worn out note.
Fair: Major tears, etc. A badly worn out note.
Poor: Even worse.
To grade a note precisely, it can help to hold the note about
20 cm (7 inches) under a strong light source (use the same source
for comparing notes) and on top of a white piece of paper and
use a 3x or 4x power magnifying glass. Make sure your hands are
clean before handling a note. This method will show a lot of
minor imperfections which are not normally visible.
Note that note from many countries have standard features which
exist for even Uncirculated notes. Some notes from Bangladesh,
Bhutan, Burma/Myanmar, India, Nepal, and Pakistan are only found
with staple holes where staples are always used to hold packs of
notes together. Most dealers list Uncirculated notes of this type
as having the usual staple holes (often abbreviated as uSH-UNC).
Also, some notes printed in France (for about 15 different
countries) have a slight crinkle effect.