Answer
(Fatwa: 1457/1372=D/1429)
If, by the experiment of the hakims and physicians, the effect of some stone is known then there is nothing wrong in wearing the same. Some things have some special effects, this is just like the herbs and medicines have effect. It is permissible to wear it for treatment of diseases. But, it is unlawful to wear them with the belief of good luck or considering it effective in itself. It is wrong to have belief of good luck about the same.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband