Answered by: Maulana Muhammad Asadullah Anwar Adam
Are crystals haram in Islam, and why?
In the name of Allah, the Most Gracious, the Most Merciful
The basic principle with regard to medical treatment is that there is nothing wrong with using anything that is proven to be beneficial and useful in treating sickness.
This applies whether its benefit is proven by shariah, as in the case of the Qur’an and honey, or through trial and experience, as in the case of all permissible remedies and medical drugs, because the Prophet (SAW) permitted treating sickness. It was narrated from Abu Hurayrah (RA) that the Prophet (SAW) said: “Allah has not sent down any sickness but He has sent down a remedy for it.” 
If something is not proven to be beneficial according to shariah or according to trial or experience, then it is not permissible to use it to treat sickness.
There is no evidence that crystals carry any healing effects.
 Sahih al Bukhari, hadith 5678
Only Allah knows best
Written by Maulana Muhammad Asadullah Anwar Adam
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham