Is the golden seal preserved in a Turkish museum, inscribed with "Muhammad is the Messenger of Allah," the authentic seal of the Prophet (peace be upon him) or is it forged, and what was the shape of the Prophet's seal with which he sealed his letters to kings?

The Prophet, peace and blessings be upon him, had a silver ring on which was engraved "Muhammad is the Messenger of Allah." This ring was lost and fell into the well of Aris. As for the ring in the museum in Turkey, its authenticity as the Prophet’s ring is questionable because there is no definitive proof for it. The Prophet's ring was made of silver, not gold, and it was lost. It appears that any golden ring the Prophet might have possessed was from before the prohibition of gold for men, after which he disposed of it. Therefore, it is almost certain that the ring [in the museum] is forged and not the ring of the Prophet, peace and blessings be upon him.