Praise be to Allah.
The Black Stone was singled out by Allah, as He prescribed for us to kiss it and touch it, and He willed that it should be set in the corner of the Ka`bah which we face when we pray. He prescribed that the people who do tawaf should touch it and kiss it if they are able to, and if they cannot do that, then they should point to it when they come in line with it, and say “Allahu akbar.”
According to a hadith narrated by al-Tirmidhi and others, the Black Stone came down from heaven, but there is some weakness in the isnad of this report. The hadith was narrated by al-Tirmidhi and classed as sahih by al-Albani in Sahih al-Tirmidhi, 695.
And Allah is the Source of strength. May Allah send blessings and peace upon our Prophet Muhammad and his family and Companions.
And Allah knows best.