It was American dancer Isadora Duncan who said: "Before I was born, my mother was in great agony of spirit and in a tragic situation. She could take no food except iced oysters and Champagne. If people ask me when I began to dance, I reply, 'In my mother's womb, probably as a result of the oysters and Champagne - the food of Aphrodite'." And so the mystique, and decadence, of oysters continue with the word "merroir" (think "marine terroir") as its chauffeur.

"The concept of 'merroir' - that an oyster takes on the flavour and essence of the water in which it's grown - is starting to take root in China, and the Chinese are looking for more flavour experiences rather than just valuing size or enjoying the species", says Travis Croxton, co-owner of Rappahannock Oyster Company in Virginia, US. "Capitalising on that concept, there are many new oyster bars that are pushing variety instead of familiarity, such as Plump Oyster, The Nest and others in Shanghai." And, like wine or whisky, oysters are becoming less a slug (appetiser, in their case) and much more a true panache delicacy.

And Kerry Heffernan, chef of Grand Banks in New York and the brand new Seaworthy at the Ace Hotel in New Orleans, agrees. "Our guests are enthralled with the subtleties and differences between oysters that exist only a few miles apart, in places like the Peconic Bay region in the Hamptons."

But it's not just about the regions anymore, everything is becoming important - from the oyster's place of growth, to its ethical and environmental impact and all the way to its age before being harvested.

Heffernan has, in fact, been experimenting with older oysters. "We have recently been experimenting with very large oysters - five years and older - and it's fascinating to dissect them with a knife and fork to see the different flavour profiles of the belly, the abductor muscle and the gills," he says.

Ryan Croxton, the other owner of Rappahannock Oyster Company, says: "We're working with Jose Andres [the famous Spanish chef] on an aged oyster, where we're taking our oysters to five years or more to see how the age affects the flavour. When these come to market, they'll be available in China, and given the age will be priced accordingly." But, the ageing trend is still in its infancy, and growers and chefs are experimenting heavily.

"Historically, eastern oysters [in Virginia] take three to four years in the wild to reach maturity [roughly five to eight cm]. Aquaculture and selective breeding have reduced that time, in many cases, to just 18 months," Ryan Croxton adds.

"Unlike cows, for instance, it isn't because of what's fed to them, hormone injections, or a lack of exercise that hasten growth. Oysters eat what's naturally in the water column, are sessile, and lack a central nervous system - so no 'doctoring' or inhumanity is at play." And so with better conditions [everything from access to food, to thinner densities of oysters], you simply get faster growth.

"The meat fattens as the animal grows more mature, so in one sense, you're literally getting more of a mouthful. In terms of taste, that's really what we aim to figure out," Travis Croxton says. "Many, if not most, vegetables get worse with age, so we could see that effect. Or we could start to see a richness and complexity develop, as you can see with beef and pork". So, it may be presumptuous to even suggest it will be better, but the Croxton brothers are betting on it. "We can mimic its natural rhythms, rather than simply let it grow, and closely monitor our success," Travis Croxton says.

But for some it's still all about size. The Americans just grade oysters by size. The French have a much more refined and special way of doing things. They have their very own classification system for oysters that are bred in the ocean and then matured in the salt basins ("claires"). "The longer the oysters mature in the basins, the more they take on the flavours from the brackish water, algae and other environmental factors - again, 'merroir'," Ryan Croxton says. "This also affects the firmness of the oyster." And so the French classify oysters in the following ways: "fines de claires" - one to two months in the basin, 40 oysters per square metre; "spéciales de claires" - four to five months in the basin, five to ten oysters per square metre; and "spéciales pousse en claire Label Rouge" - four to eight months in the basin, five oysters per square metre. The last one is what the two brothers Croxton would call the "most closely regulated and exclusive".

Speaking of exclusive, there are some oysters that are just harder to come by and so a whole lot more desirable. According to the Croxton brothers, there are two ways to look at rare oysters - rare in terms of availability in Hong Kong and mainland China, and rare in terms of species population. The former is the "crassostrea virginica" or East Coast oyster. "China appears to have first been invaded by the French oyster, then Australia/New Zealand, and now the Pacific Northwest, but you're not seeing anything from the East Coast of the US, so you're not seeing 'Virginica' anywhere," Ryan Croxton says.

And for an oyster hunt, the rarer species range from "ostrea edulis", commonly known as the European flat oyster, which famously the Romans fawned over; "saccostrea glomerata", called the Sydney rock oyster); to the "ostrea lurida", commonly called the olympia oyster.

But then there is the Gillardeau fourth generation oyster dynasty in western France taking it all to another level. Founded in 1898, it only produces "spéciales" oysters that are fleshier and, therefore, more expensive than anything else on the market. "They [Gillardeau] raise their oysters in a very specific way and laser-etch a 'G' onto each one to ensure its provenance," Travis Croxton says.

For Grand Banks, they serve "Kumamotos" which Heffernan calls special as they are "hard to raise and increasingly rare".

Asking Ryan Croxton about the more expensive oysters available in the world, he cites Taylor Shellfish that grows a "shigoku" oyster that uses a French rack technique. "The oysters are naturally tumbled twice a day as the tide comes in and goes out. The technique ends up shaping the oysters into this little ball. "It's beautiful and it also has nice plump meat," he says.

Whether you're eating oysters in a new naked and raw way to experience "merroir" or whether you're going old school with steamed oyster dishes in New Orleans and the south of America, oysters are getting some well deserved love and experimentation. Keep ignoring those pearls and focus on finding the wild oyster crusaders - they are certainly out there.

• 

  Johannesburg: After a major refurbishment, it's perhaps the best time to get down to Eighteen 05 at the Saxon in Africa's primary city. Nelson Mandela was a regular here.
• New York: Ocean Prime, in Manhattan's midtown, from restaurateur Cameron Mitchell, is intimate and the perfect venue to slurp down oysters paired with Champagne. And it supports the Billion Oyster Project in the city.
• Melbourne: The family run Richmond Oysters in downtown Melbourne is where to shuck oysters with some friendly folks. Of course the wine list is endless.
• Buenos Aires: Pony Line, inside the Four Seasons Hotel, is where to meet friends and indulge in the city's finest oysters. Most nights this turns into tango too.
• And if you're in Hong Kong: Felix, designed by Philippe Starck, offers iconic views and some of the city's finest oysters.

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