Dr Eléonore Cellard noticed Coptic letters faintly behind the Arabic script which prompted her to contact Christie's auction house, who managed to identify the text as being from the Old Testament's Book of Deuteronomy.
The artifact sold for almost £600,000 at Christie's auction house on Thursday - more than five times the guide price.
The "extraordinary" artefact is unique as it dates back to the earliest days of Islam. It is the only known example where passages from the Bible have been recycled so pages could be reused for Muslims' holy book.
Cellard, a French scholar from Collège de France, told the Daily Mail: "This is a very important discovery for the history of the Qur'an and early Islam.
"We have here a witness of cultural interactions between different religious communities."
Praising Cellard's discovery, Christie's auction house specialist Romain Pingannaud told the Guardian: "Once you know it's there, you can only see it, it becomes so obvious. We missed it at the beginning.
"It's fascinating, particularly because it's the only example where you have an Arabic text on top of a non-Arabic text. And what's even more fascinating is it is on top of passages from the Old Testament ... It shows the contact between communities in the first centuries of Islam; it's very relevant."
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