The cast-iron sign is a tribute to the 38 men, women and children from the MacDonald clan who were murdered there in February 1692.
It is believed to be at least 100 years old and was thought to have been irretrievably lost after it was removed from its berth near the Pap of Glencoe.
However, in September last year, antique dealer George Pirie stumbled upon the sign in Edinburgh and placed it in his Howe Street shop. Its significance was only recognised when a woman - also a MacDonald - asked if it was the original which she had seen in Glencoe in the 1960s.
Mr Pirie said: "She had a picture of her with the sign taken years before, but it had been a different colour at the time. We started chipping away at the paint and right enough, it was the same underneath."
Mr Pirie has since been in contact with the Glencoe Heritage Trust and has agreed to place the sign back at its original position.