What is the ruling of Islamic Law on wearing energy stones?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
There is no objection to a woman adorning herself with precious and semi-precious stones — such as ruby, carnelian, or the like — so long as these are stones that women customarily wear as adornment.
As for what are known as "energy stones," if they are used with the intention of seeking remedy and healing, then such matters are governed by experimentation and scientific study — which either establishes that they have a tangible effect or does not — and all of this operates by the permission and will of Allah, Glorified and Exalted. If studies or practical experience do establish that such stones carry a beneficial effect upon human health, then there is no objection to using them. They are, after all, part of Allah's creation, much like medicinal substances extracted from plants or derived from other created things — provided that the Muslim does not believe that the stone itself is the source of benefit or harm. It is nothing more than a means among the many means that Allah has placed in this world, and the reality of all affairs belongs to Allah alone. And Allah the Almighty knows best.
What is the ruling on giving the expiation of an oath (Kaffarat al-Yamin) to a charity that feeds the poor?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is allowed for a Muslim to appoint a proxy (agent) to distribute the expiation (Kaffarah) on their behalf. Our jurists have explicitly stated the permissibility of delegation (Tawkil) in the distribution of Zakat, Kaffarah, and vows (Nadr).
It is stated in Mughni al-Muhtaj (Vol.3/P.237): 'One has the right to pay the Zakat of their wealth personally... and they also have the right to delegate it.' And Allah the Exalted knows best.
Which hour coincides with the last third of the night?
This hour could be figured out by calculating the number of night hours which start at sunset, and end at dawn break, then the total is divided on three to get the result.
Is it a condition for the mosque where I‘tikaf is performed to hold Jumu‘ah prayers?
No, it is not a condition for the mosque where I‘tikaf is performed to have Jumu‘ah prayers. However, if a person vows to perform continuous I‘tikaf, and Jumu‘ah occurs within that period, then they must observe I‘tikaf in a mosque where Jumu‘ah is held so that they do not break their continuity by leaving for Friday prayer.