There are 2 parts to Diagnosis in Traditional Chinese Medicine
1) Diagnostic Methods
a) Four Examinations
2) Differentiation of Syndromes

Diagnostic Methods
1) The Four Examinations
The TCM Physician performs an inspection of the patient that divides into 4 stages. The 4 Stages are called the four examinations, because each one focusses on a different way of recognizing signs in a patient.
The 4 examinations are:
1) Looking (visual observation)
2) Listening and Smelling (oscutation and olofaction)
3) Asking (Inquiry)
4) Touching (palpitation)--pulse, touch

The physician completes each of the examinations gathering signs to weave into the final diagnosis. Strictly speaking, however, accurate diagnosis can be made by synthesizing data from all 4 examinations.
I. Looking
In the looking examination, the physician attends to 4 characterisitics that are visible to the eye. The first is general appearance, including the patient's physical shape, the patient's manner, the state of a patient's shen (spirit/vitality).
The second is the facial color and the color of the other skin and the eyes.
The third is the tongue, including the material of the tongue itself, (sometimes called the tongue proper), the coating of the tongue (fur or moss), and its shape and movement.
The fourth is the body's secretions and excretions.

I. General Appearance
1) Observation of Shen (spirit, vitality)
To observe the patient's appearance, facial expression, speech, response to inquiry, etc.
a) spirit and energy in vigour (having stong vitality)--spiritedness.
We all know the expression is the outward manifestation of the vital activities. If the patient has bright eyes, normal bearing, clear speech, and responds coherently to inquiry, the condition is said to be spirited. This indicates that the patient's correct Qi (healthy energy) is good.
b) Spirit and Vital energy are in depletion (lack of vitality)
If the patient has manifested dull eyes, low in spirits, weak respiration, shortness of breath, sluggish response, or even unconsciousness, white face or wan looking, low voice, apoplectic stroke with closed eyes and open mouth, and uresis. Does not cooperate during examination. This 'means' that the healthy energy is damaged. The disease is serious, and the prognosis is bad.
c) Pseudo-spiritedness
This condition usually seen in patients with chronic diseases, severe illness, and extremely severe cases. if, suddenly, during a disease characterized by taciturnity, a low voice, halting speech, and an extremely dark complexion, the patient becomes strangely grrulous, and the patient's cheeks are flushed and unusually rosy, this new phenomenon is said to be one of false spiritedness. Such conditions are very serious, and should not be mistaken for improvement. It is a sigh the the patien's condition will soon deteriorate dramatically.
Pseudo spiritedness also can be seen in patients in the following diseases such as psychosis, apolepsy, mania, etc. The patient's manifested as indifferent or apathetic expression. Habitually silent (taciturn), unhappy, stupor, sometimes cry, sometimes smile.

2) Color--face
People of different races have different skin colors, and there is wide variation amond people of the same race, however, a lustrous skin with natural color. E.G. The complexion of a healthy Chinese person is slightly dark, but shining and ruddy.
1) White or pale colour complexion usually indicates deficiency, cold, or syndrome of blood loss (similar to anemia) as deficiency of the Yang energy. The patient with yang deficiency manifests as fatigue, shortness of breath, intolerance to cold, (Dressing a lot in summer) cold extremities, etc. Powerlessness or vital energy and blood. Exhaustion of vital energy and blood losing. The patient's all have white faces. A pale, white, lusterless complextion together with general and facial emaciation normally point to blood deficiency. A drained, white complexion with facial edema generally indicates yang Qi deficiency and sometimes occurs after massive bleeding or impatience of chronic nephritis.
If this occurs suddenly in an acute disease, it usually indicates collapse of yang qi (shock). Sombre white complexion may be seen in cases of exogenous wind/cold diseases characterized by aversion to cold, shivering, etc, and severe abdominal pain due to interior cold.

Shen (italics denote definitions of terms)--spirit vitality.
1) A general term for the life activities, including the external appearance of the physiological or pathological condition of the body, which are the major criteria for diagnosis
2) Mind--referring to thought and state of consciousness.
Correct Qi--Referring to the resistance of the human body to disease.
Depletion of spirit--A morbid state due to serious impairment of the vital activities of the human body, and the exhaustion of essence energy of the five viscera; manifested as lusterlessness of the eyes and emaciation, intractible diarrhea, mental disorder, sudden syncope.
Deficiency syndrome--A syndrome produced by deficiency of vital energy and essence, lowered resistance and hypofunction of the body. Commonly seen in an individual with general debility and the patient suffering from a long-standing illness; manifested as lusterless complexion, listlessness, shortness of breath, weak voice, palpitation, insomnia, poor appetite, thick and tender tongue, feeble pulse, etc.
Cold 1) Referring to cold evil--one of the six evils which is Yin in nature. Usually damages Yang energy and affects the activity of vital energy and blood. It may cause the symptoms such as chilliness, fever, headache, general aching, abdominal pain, diarrhea, etc.
2) Diseases characterized by the hypofunction of the body.
(Six evils (Six external pernicious influences, climates)--wind, cold, summerheat, dampness, dryness, fire)
Yang energy--The opposite of Yin energy. As for the function and morphology, yang energy stands for function. As for the physiological and pathological phenomenon, yang energy stands for those which are external, upward, hyperfunctioning, reinforcing, light, etc.
Exhaustion of vital energy and blood losing--A morbid condition of collapse of Yang energy after massive hemorrhage because of lodgement of vital energy; manifested as pallor, cold extremities, profuse perspiration, weak or impalpable pulse, etc. Corresponding to hemorrhagic shock in Western Industrial Medicine.
Blood Deficiency--Usually caused by blood loss or asthenia (deficiency) of the five viscera. Manifested as pallor, dizziness, palpitation, insomnia, numbness of extremities, small and weak pulse, etc.
Spiritedness--A healthy state in which the vital functions of the human body are active, manifested as fully conscious and normal functions of all organs.
Deficiency of Yang Qi--A cold syndrome in the interior resulting from the insufficiency of Yang Qi; the patient manifested as fatigue, shortness of breath, intolerance to cold, cold extremities, spontaneous perspiration, pallor, polyuria with watery urine, diarrhea, pale, tender tongue, feeble, large pulse.
Interior Cold--A disorder with retention of fluid caused by the deficiency of Yang energy and the hypofunction of viscera manifested as vomiting, diarrhea, abdominal pain, cold hands and feet, clammy perspiration, sunken and slow pulse.