In 1586 William Camden described the remarkable cliffs of the Avon Gorge, Bristol, in his book Britannia:

“From hence as Avon holdeth on his course, there are on ech side very high cliffes…which are so full of Diamants, that a man may fill whole strikes or bushels of them. These are not so much set by, because they be so plenteous. For in bright and transparent colour they match the Indian Diamants; in hardness only they are inferior to them.”

In fact, what Camden described was not diamonds at all, but multi-faceted quartz crystals that became known as ‘Bristol Diamonds’. Now recognised as quartz geodes, they are believed to have formed in the cavities of fossilised scree, which was deposited about 250 million years ago against the sides of long-since eroded mountains. Water percolating through the scree carried silica in solution that was precipitated in the hollows where there was space for the beautiful quartz crystals to grow.

Camden’s observation that Bristol Diamonds were not as hard as real (Indian) diamonds, was correct. On a scale of hardness for naturally occurring minerals, real diamonds are at the top with 10, while quartz is only 7. Nevertheless, Bristol Diamonds were in great demand for jewellery at that time.

Today it is difficult to imagine what the diamond-studded Avon Gorge must have looked like in the 16th century, long before Brunel’s Suspension Bridge was built. Collection during that period has completely removed them, although a few can occasionally be found on beaches and in quarries around Bristol.