Almost all Sadhus and Sannyasis that we see wear malas made of rudrakshas.I think for them the reasons are spiritual.
But even a common man can wear a rudraksha.For them the reasons can be spiritual or astrological or both.
Rudrakshas can be of various kinds and specific rudrakshas are often worn as remedies for specific malefic planets.
For eg-for malefic Sun,1 mukhi or 12 mukhi are recommended,for malefic Moon 2 mukhi ,for malefic Mars 3 mukhi and so on.
This Devi Bhagavatam chapter contains a lot about rudrakshas and the benefits of wearing them.
The origin of Rudrakshas [dark beads of Tree, termed Elaeocorpus Ganitrus in Latin language] or Lord Siva’s tears, extensively used as Prayer Rosaries, goes back to Maha Deva’s killing Tripurasura......
Some restrictions are there .Few are given below:
All vedic acts are to be accompanied by wearing Rudraksha Malas like Sacrifices, Vraths, Pujas, holy baths, Shraddhas, Solar and Lunar Eclipses, Uttarayana and Dakshinayana ‘Samkramanas’(entry timings), and Full Moon and New Moon days or Pournami and Pradhama days.However one should not touch or consume wine, meat, tobacco, onion, garlic and such impurities as also during mating, since these constitute atrocious insults to Maha Deva
Who can wear them?
The white variety of the beads are meant for wearing by Brahmanas, the red colour by Kshatriyas and the black coloured beads by Vaisyas and others
But it is not clear to me whether this others include women or not.
Question-Are women allowed to wear rudrakshas?