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.
Is it permissible to offer mandatory prayer while sitting?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions. Standing up is a pillar in the mandatory prayer and the prayer is not valid without it unless one cannot do it. As for Nafila (supererogatory prayer), one can perform it in the state of sitting even if he/she can stand, but his/her reward is half the reward of the person who prays while standing if he/sh has no legal excuse for such an act. And Allah Knows Best.
Is Fajr (dawn) Sunnah a confirmed one?
All praise be to Allah The Lord of The Worlds Of course, it is a confirmed Sunna which the Prophet (PBUH) used to offer in a regular basis. And Allah Knows Best.
What is incumbent upon the one offering the sacrifice if, after slaughtering the animal, they discover that one of its internal organs is damaged or diseased?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The presence of disease or defect in the internal organs of a sheep does not affect the validity of the sacrificial animal, unless the disease leads to the animal becoming emaciated and its meat becoming corrupted.
It is stated in al-Iqnā' (2/590) by Imam al-Shirbīnī: "The third disqualifying condition: an animal with a manifest illness — meaning one whose illness visibly results in emaciation and corruption of its meat. However, if the illness is minor and does not produce such effects, it doesn`t affect the validity of the sacrificed animal." And Allah Almighty knows best.