This is the oldest complete, dated, printed book in the world. It was block printed in 868 AD as attested by a colophon included in the book. Seven strips of yellow-stained paper were printed from carved wooden blocks and pasted together to form a scroll over 5 meters long which was wrapped around a wooden roller. There are earlier block-printed books but this is the earliest complete one with a firm date of origin.
A sutra, a Sanskrit word, is a religious teaching or sermon. The word is most often used to describe the teachings of the Buddha.
This fascinating video from the British Library tells of the Sutra’s discovery by Sir Aurel Stein in a cave at Dunhuang, on the Silk Road, and shows the process of conservation which took the Library over a decade. A section of The Diamond Sutra may be seen in the Ritblat Gallery on the first floor of The British Library. I’m not sure whether it is always on display there in the “Treasures of the British Library” exhibition or just occasionally.