Rob Carter's interest in pearls began almost a decade ago, during excavations by the Kuwaiti-British Archaeological Expedition of H3, a fifth- and sixth-millennium site at the north end of Kuwait Bay.
Starting in 1998, over the next five years the expedition unearthed a great deal, including pottery, tools, bitumen and even a ceramic model of a reed boat, which not only painted an intriguing picture of the complex trading networks that linked the neolithic world of the Gulf, but also provided the first evidence that the horizon-broadening technology of the sail was known in the region as early as the sixth millennium BC.
But Carter, one of the expedition's field directors and an archaeologist with the Institute of Archaeology at University College London, was taken by one of its smallest finds - a pierced, time-tarnished pearl, barely 4mm across.
A few years earlier, another lone pearl from a later period had been found during the excavation of a neolithic graveyard in Sharjah, but the H3 find was the earliest artefactual evidence of pearling in the Middle East. By chance, that same year another pearl was unearthed by archaeologists excavating a tomb in Umm al Qaiwain.
Carter's professional interest was piqued. "I did a bit of due diligence on pearl finds in the Gulf and found there was a huge amount of information on the historic fishery, and things mushroomed."
The first result was an exhaustive academic paper, The History and Prehistory of Pearling in The Persian Gulf, which was published in 2005. The article caught the eye of the London-based publisher Arabian Publishing and now Carter is reading the final proofs of what his publisher describes as "a milestone in history writing on the Gulf".
When it is published early next year the book, Sea of Pearls: Arabia, Persia, and the Industry that Shaped the Gulf, will be the first definitive telling of the history of the 8,000-year industry throughout the entire Gulf, from neolithic times until its final collapse in the middle of the 20th century - a story which, says Arabian Publishing, "surprisingly, has never before been attempted".
At 165,000 words and 380-plus pages, packed with more than 350 photographs, the book is in more than one sense a heavyweight contribution to the history of the region - and much more, says Carter, than a mere coffee-table book.
"It is a large book, lavishly illustrated in colour," he concedes, speaking by telephone from London and taking a brief break from packing in readiness for a move to Qatar; next month he takes up a new post on UCL's new campus in Doha, where he is setting up a centre for teaching and research in the archaeology and heritage of the Arab and Islamic world.
"But despite the glossiness of the illustrations, it's actually quite academic. We are hoping it will interest not only researchers but educated readers who have an interest in the region as well.
"So it's not a coffee-table book, but some of the kind of people who read coffee-table books will, I think, find it interesting."
While evidence of human fascination with these iridescent objects dates back to antiquity, for Carter "when it gets particularly interesting from my point of view is when you hit the 18th century". This, he says, is "when the pearl fishery starts changing the fabric of the region".
From our perspective on the far side of the oil boom, it is, as he says, startling to consider that "any town, pretty much, that you can name in the Gulf today was founded as a pearl-fishing town within a couple of hundred years in the 18th or 19th centuries" - including Dubai, Abu Dhabi, Kuwait City and Doha.
For many, the growth of the towns spelled the withering of the Bedouin way of life.
"The long boom began in or before the 18th century, which caused the foundation of these pearling towns. This is where most of the population was. Many previously nomadic groups settled in the towns and ceased to be Bedouin."
Not that anyone was complaining. Pearling was a tough business, but life was harsh in the desert and, for the first time, the pearl boom opened a door to upward mobility for Arabs from the interior.
"An Arab tribe or group would come to the shore and join a town, maybe seasonally, and begin pearl fishing. When they'd made enough money they would own the boats and maybe employ other people.
"That's not to say there weren't a lot of Arab people still diving, right up to the end of the industry, because not everybody had money.
"But there does seem to be a pattern that when you make money you can stop doing the nasty bit, get yourself a boat or two and maybe you, or your son, can become a merchant in the long run."
Carter has drawn extensively on the detailed records kept by the British government of India, compiled chiefly by John Gordon Lorimer of the Indian Civil Service. Lorimer's six-volume Gazetteer, researched over 10 years at the turn of the century and published in 1908 and 1915, is the single most valuable source of historical, political, geographical, commercial and statistical information about life in the Gulf, back as far as the 1500s.
These records show clearly, says Carter, that by the end of the 19th century "at least half and probably more of the hard cash that was coming into the region was from pearls ... pearling was what everybody did and pearl fishing provided pretty much all of the money".
And a lot of money it was, too.
Figures from Lorimer and others show that by 1907 more than 70,000 men were working in pearling and that by 1903-04 the total value of exports from Trucial Oman, Bahrain and the Persian coast exceeded 24 million rupees.
But the pearl was prey to the whims of western fashion.
"Pearling first started having a structural influence on the way in which the Gulf was configured socially, and in terms of its urban set-up, much earlier," says Carter, "but then it really accelerates at the end of the 19th century and that's entirely due to fashion in the West."
As the western middle classes multiplied and demand for the symbols of success grew, there was "an extraordinary boom in prices", as much as twelvefold, between about 1890 and the First World War. The pearl's ostentatious zenith came in 1917, when Pierre Cartier opened his New York branch, acquiring the Fifth Avenue premises from the son of a railway tycoon in exchange for US$100 in cash and a string of pearls, valued at US$1 million.
Pearls might have survived the slowdown caused by the First World War - "due to lack of confidence and communications", says Carter, "but also because in times of war people don't spend their money so much on fripperies" - and indeed there was a minor recovery when peace came.
Cultured pearls, which would eventually spell the end of the pearl fisheries, first appeared in about 1925, "but the thing that really killed off the industry was the Wall Street crash in 1929, and the loss of markets".
Prices dropped like a stone, to the levels of the early 19th century.
In the Gulf, the crippled industry staggered on, simply because people had no alternative, but they faced difficult years ahead, with no apparent end in sight. "You had these huge coastal populations in these towns, they had been there for a couple of generations or more and they had nowhere to go back to, no way of earning money, so if they could earn just a few rupees pearl fishing then they would do it." It was, he says, "very tough. A population had built up which didn't have flocks and gardens to sustain them."
The story does, of course, have the happiest of endings. Eventually oil would save the day and pearling would take its final bow - in the Fifties in Bahrain, where oil was discovered first, and about a decade later in the Emirates.
There is, says Carter, no doubt that without the coming of the black stuff the towns built on pearls "would have eventually died and become fishing villages or completely vanished". Abu Dhabi, he thinks "would have vanished very quickly if they hadn't been kept going for about 30 years on oil concession money", paid by western companies for the right to look for oil. "It wasn't enough to make anyone rich, including the sheikhs, but it was enough to keep people in the towns."
In a way, Lorimer had seen it coming. Without pearls, he warned in 1915, "the ports of Trucial Oman, which have no other resources, would practically cease to exist".
It was a close-run thing.