I want to wear the Rudraksha Bead, but have some queries related to the rules. So please let me know the exact rules for it.
The Rules for wearing Rudraksha are discussed in Vidyes’vara Samhita ,Chapter 25 (The Glory of the Rudraksha) in Shiva Maha-Purana.
These are some of the Rules -:
शिरसीशानमन्त्रेण कर्णे तत्पुरुषेण च |
अघोरेण गले धार्यं तेनैव ह्य्रुदयेsपि च ||40||
One should wear Rudraksha reciting the Isana-mantra ,with Tatpurusha in ears and with Aghora mantra , over the heart.Rudrakasha thus be worn.
मद्यं मासं तु लशुनं पलाण्डु शिग्रुमेव च |
श्लेष्मान्तकं विड वराहं भक्षणे वर्जयेत्ततः ||43||
A person wearing Rudraksha beads ,shall not eat meat ,garlic ,onion ,red garlic potherb glutinous fruits ,pig of rubbish and wine.
वलक्षं रुद्राक्षं द्विजतनुभिरेवेह् विहितं
सुरक्तं क्षत्राणान प्रमिदितमुमे पितमसकृतं
ततो वैश्येर्धार्यं प्रतिदिवसमावश्यकमहो
तथा कृष्णं शुद्रै: श्रुतिगदितमार्गोsयमगजे || 44 ||
O Parvati ,the White Rudrakasha should be worn by the Brahmanas , the Red by Kshatriyas ,yellow by the vaishyas ,while the black should be used by the Sudras.This has been propounded by the Vedas.
उपवीते त्रयं धार्यं शिवभक्तिरतैर्नरै:|
शेषानृर्वरितान्पच्त्र सम्मितान धारयेत्कटो: ||30||
A Devotee of Shiva Should wear three beads in the yajnopavita and five in waist.
धात्रीफलप्रमाणं यत् श्रेष्ठमेतदुदाहॄतम् ।
बदरीफलमात्रं तु मध्यमं संप्रकीर्तितं ॥14॥
Rudraksha of size of Embolic Myrobaln is considered to be the best.The one is size of Jujube fruit is considered to be the middle one.
Adding one important rule which the selected answer has not mentioned. Apart from energizing the Rudraksha beads with Panchakshara and Trayambaka Shiva mantras, each of the 14 types of Rudrakshas has to be worn by the devotee only after chanting a particular mantra that is associated with that particular type of Rudraksha .
By not doing so one accrues sins. The 14 mantras can be found in both Padma and Skanda Puranas with some variations.
NischidrAscha SupakkAscha RudrakshadhArane SmritAha |
PanchAmritam Panchagavyam SnAnakAle Prajojayeth |
RudrAkshasya PratishthAyAm Mantram PanchAksharam TathA |
TryambakAdimantrancha TathA Tatra Prajojayeth |
Only ripe ones and Rudrakshas which are free from holes are good to wear. During the pranpratishtha of Rudrakshas they are to be bathed first with panchagavyas ( 5 things from cow like her urine, milk etc) and panchamritas ( milk, ghee, sugar etc) and then energised with panchakshara, tryambaka and other Shiva mantras.
And here is the warning i am talking about:
VinA Mantrena Yo Dhatte RudrAksham Bhuvi Manavah |
Sa YAti GhorAn YAvadindrAschaturdasa |
Iti Padma PurAne RudrAkshyamAhAtyam..
One who wears Rudraksha without mantra lives in dreadful hells for as much amount time as long as the 14 Indras rule.
Verses are from Padma PurAna.
And, the 14 mantras given in Padma PurAna are as given below:
Tatra Kramena MantrAha | OM OM Bhrisam namaha (for one-faced Rudrakshas), OM OM Namaha (for two-faced ones),........ OM Namo Namaha (for 14-faced ones).
As you can see, omitted most mantras as they are to given by the very knowledgeable person who prescribed a Rudraksha for you.
In Skanda PurAna , however, different mantras are given. Here are a few samples of them:
OM Aim (for one-faced), Om Srim (for two-faced)................... OM TamAm (for 14-faced).
Updating the answer with more relevant information found in the RudrAksha JabAla Upanishad (which is linked to the SAma Veda).
One who wears Rudrakshas, should not use intoxicants, meat, garlic, onions, carrots and all such prohibited things. By wearing Rudrakshas during eclipses, Vishusankranti (the end of Mina and beginning of Mesha Masa), new moon, full moon and other such auspicious days, one is freed of all sins. The base of the Rudraksha bead is Brahma, its navel is Vishnu, its face is Rudra and its hole consists of all gods.
The four kinds of people, Brahmins, Kshatriyas, Vaisyas and Sudras are born as merely a worthless burden on the earth. The real Brahmin is the white Rudraksha. The red is a Kshatriya. The yellow is a Vaisya. And the black is a Sudra.
Therefore, a Brahmin should wear white Rudrakshas, a Kshatriya the red, a Vaisya the yellow and a Sudra the black. One should use those Rudraksha-beads which are nice, goodlooking, strong, big, auspicious and thorny. One should avoid those eaten by worms, broken, without thorns, and having sores.
There are also many kinds of them (as already noted), like one-faced, two-faced etc till fourteen faced. One needs to know which one is he wearing.
Lord Kalagnirudra said: The bead with one face is of the form of the Supreme Truth. A disciplined one (controlling his senses) mingles himself with the one Eternal Truth, after wearing these Rudrakshas. The bead with two faces is of the form of Ardhanarisvara and the devotee wearing it attains the grace of Ardhanarisvara (Siva united with Sakti). The bead with three faces is of the form of the three fires and the devotee wearing it attains the grace of Agni. The bead with four faces is of the form of the four-faced Brahma and the devotee wearing it attains the grace of Brahma. The bead with five faces is of the form of Panchabrahman (the five-faced Siva) and the devotee wearing it attains the grace of Panchabrahman and drives away the sin of homicide. The bead with six faces is of the form of the six-faced Kartikeya or Ganesha and the devotee wearing it attains the grace of wealth and health, clear intellect and wisdom, and purification.
And, if you know your type, but do not know which Mantra to chant before wearing it, then you can consult this page.
So, if your RudrAksha is five-faced, for example, then you have to check this page to find the Mantra. And, it gives the following Mantra:
Om Hreem Namaha