The 1922 “plain” or “no d” can be produced from four different die pairs.  Die Pairs #1, #3  and #4 produce either
a “weak D” or a “No D”.  Die Pair #2, which is the most desirable of the four die pairs, always produces a “No D”.  

In 1922 only the Denver Mint was responsible for producing Lincoln Cents.  Both Mints were busy producing
millions of Silver Dollars.  No nickels, dimes, quarters, or half dollars were produced in 1922.   The creation of all
four die pairs was the result of the Denver Mint running out of usable dies with thousands of cents needed to be
struck to fill their quota.  

Die Pairs #1,  #3 and #4 were the result of “mint grease”, which is a combination of dirt, metal, and oil, filling the
area of the mintmark.  Mint grease would fill the mintmark gradually, resulting in different levels of “weakness”.  It
is believed that the mint grease would fall out, then refill creating a cycle of normal D’s, broken D’s, weak D’s, and
no D’s.  When looking at circulated examples of 1922 D’s, keep in mind that the mintmark could have simply be
worn from use.  Die Pairs #1, #3 and #4 have “weak reverses” because they were struck with worn reverse dies.  

Die Pair #2 is not believed to be the result of “mint grease”.   A pair of dies that were creating 1922 D’s clashed
together.  The clash resulted in damage to both the obverse and reverse die.  The reverse die was badly
damaged, and replaced with a newer less worn die.  The obverse die was reworked by a mint employee who
erased all traces of the D mintmark while repairing and polishing the die.  The result is a worn obverse die with no
trace of a mintmark and a strong reverse die.    

All 1922 weak D or No D coins fall into one of 7 categories:
1.        Die Pair #1  Weak D  (Weak Reverse)
2.        Die Pair #1  No D (Weak Reverse)
3.        Die Pair #2  No D  (
Strong Reverse) also called 1922 Plain
4.        Die Pair #3  Weak D (Weak Reverse)
5.        Die Pair #3  No D (Weak Reverse)
6.        Die Pair #4  Weak D (Weak Reverse)
7.        Die Pair #4  No D (Weak Reverse)

PCGS, NGC and some other grading services do not distinguish between the seven varieties above.  PCGS and
NGC authenticate Die Pairs #1, #3 and #4 as either  “1922 weak D” or “1922 No D weak reverse”.  Die Pair #2 is
authenticated as “1922 No D
strong reverse”.   

ANACS does things a little bit differently.  Only Die Pair #2 is given a “No D” classification.  Die Pairs #1,  #3 and
#4 are
all classified as “Weak D’s” regardless of the strength of the mintmark.   

Below is an explanation of how to classify the four Die Pairs:

Die Pair #1:
•        The easiest way to classify Die Pair #1 is the Jogging Die
Crack running from L in Pluribus through O in One.  
However, this die crack is not always present.   Also, be
aware that there exists a 1922 D variety with a straight die
crack in the same location.   
•        The second 2 in date is weaker than the first 2.
•        The first T in Trust is more distinct than the other letters.  
Furthermore,  the T, U, and T in TRUST are stronger than
the R and S.   
•        WE is very mushy.
•        Reverse is very weak, usually with no lines in the wheat ears.
•        Mintmark ranges from Weak to No D.

Die Pair #2:
•        Absolutely no trace of a D
•        Second 2 in date is sharper than the first 2.
•        All letters in TRUST are sharp.
•        WE is only slightly mushy.
•        L in LIBERTY butts up against the rim.
•        Reverse is sharp with nice wheat lines.

Die pair #3:
•        Second 2 in date is weaker than first 2.
•        TRUST is weak but sharper than IN GOD WE.
•        L in LIBERTY butts up against the rim.
•        The reverse is slightly rotated counterclockwise
•        Reverse is weak -- lower left part of O in ONE begins to
spread into the field as the die deteriotates.  Reverse looks "wavy"
•        Mintmark ranges from Weak to No D.

Die Pair #4
"The front of Lincoln's coat from about 4 o'clock to 5 o'clock   
appears to merge into the rim whereas Dies 1-3 all have a
regular pronounced gap between the coat
and rim.  This merging is responsible for Die 4's nickname,
"coattails."   The reverse is noted for its weak high point detail,
similar to Die 1 and Die 3." -   Andrew Vickery ANACS Grader

It is recommended that collectors invest in certified examples of “No D” varieties.  
1922 No D and Weak D Varieties
Die 1 Jogging Die Crack
1922 D Straight Die Crack
All images courtesy of Heritage Auction Galleries