Lord Shiva's mantra "Om Namah Shivaya" or any other mantra chanted with Rudraksha mala gives unlimited benefits as told in Shiva Purana.
The number of the beads of mala depends on the aim of chanting mantras. The mala of 108 + 1 = 109 beads is regarded the best to count mantras. There are three kinds of malas. One of them includes 108 beads + 1 bead called sumeru. The other one includes 54 beads + 1 sumeru. If it is counted twice, it completes one mala. The third kind of mala includes 1/4 beads of a full garland i.e. 27 beads + 1 sumeru. This is called 'sumarni'. Four times of this mala completes one full Mala of 108 beads. This sumarni is good for the man who remains always busy with chanting mantras and meditation. It is easily portable. Garland of 132 beads is useful for performing rituals to get riches. A rosary of twenty five beads renders Moksa (liberation) ; that of thirty beads renders wealth, that of fifty beads renders prosperity and that of fifteen beads is helpful in spells for a malevolent purpose . While wearing a rosary of 27 beads if a man does rituals , he gets a crore times more benefit . Vopadeva states in Padarth-Darsa that one who wears thirty two Rudrakshas in neck , forty on forehead , six in each ears , twelve in each wrists , sixteen in each arm , four on each eye , one hundred and eight over the chest , himself becomes NeelaKantha (Shiva).
There is a mention of merits of rosary in chanting mantras (mystic syllables) by the combination of different fingers for different purposes in some other mystic literatures. It is said that in handling the rosary only forepart of the fingers should be used. There is a prominent bead, which is normally the central portion of the rosary and is called Meru. The Sadhaka while rotating the rosary should not overtake this Meru while counting and from there he should count the recitations in the reverse order.
The Method of Counting Beads :- Japa, the counting of beads, should be done after covering the mala. Mala should be kept always in a cotton bag (Gomukhi) and during the counting of beads of mala , the hand should be inside the gomukhi . While counting mantras the mala should not touch the ground at any time . There is another method for Japa - Take a copper bowl filled with water and now half of the beads of the mala remain in hand and rest of the mala beads must remain sinking in the water. Now cover the hand with a cloth and start to do the japa. After complete the japa (reciting the mantra), this water should be sprinkled in the house, in the courtyard and it should be drunk. Doing so the person gets happiness and he marches towards salvation.
Besides the Pauranic versions for the uses of Rudraksa, there is mention of merits of their rosary in chanting mantras (mystic syllables) by combination of different fingers for different purposes in some other mystic literatures (Shubhankaran, 1991). It is held that in handling the rosary only fore part of the fingers should be used. There is a prominent bead, which is normally the central portion of the rosary and is called the Meru . The person should not overtake this Meru while counting and from there he should count the recitation in the reverse order. While counting the rosary should be revolved in a direction towards the person.
Mantra for the attainment of final salvation or religious perfection should be recited by revolving the rosary with thumbs and Index finger ( also called Tarjani i.e. first finger or the finger of Jupiter). The finger of Jupiter is also used for destroying enemies. Mantras for peace should be recited with the help of thumb and second finger ( also called Madhyama or finger of Saturn) and for the attainment of mantra siddhi with thumb and third finger or ring finger or finger of Sun). Thumb is used for final emancipation, finger of Jupiter for the prosperities through trading and business; finger of Saturn for wealth and happiness; finger of Sun for peace and finally anamika or finger of Mercury for all types of mantras, Siddhis, etc. Revolving rosary with thumb, middle and ring finger helps attaining peace and mental tranquility.