Going off the boil but returning infused: Joanna Blythman, a confirmed coffee-drinker, went unwillingly to Mariage Freres, a specialist tea shop in Paris, and found herself completely seduced

When I went to investigate a shop in Paris that sells specialist teas, I did not expect to be thrilled. I have sipped the contents of those tricksy wooden boxes. I have been down the Chinese up-market, enthusiastically buying packets with inscrutable text and curious shapes, to drink the tea once and then forget it. I have even become fond of a few. Whittards of Chelsea's Pelham blend is agreeable, and I would make a detour for Taylor of Harrogate's Formosa Island Lapsang Souchong.

But this was just a drop in my personal ocean of fidelity to the coffee bean in all its fascinating forms. Faced with the choice between absolutely any tea and the complex charms of volcanic lava coffee, I had no doubt where my allegiance lay. Until I stepped over the threshold of Mariage Freres's magnificent establishment in the historic Marais quarter of Paris, and entered a scented and seductive world of tea.

The first shock is the attack on one's prejudice. What do the French know about tea, after all? I had swallowed all that guff about the British pre-eminence in all things tea-related. But a mere glimpse of the list on sale at Mariage illustrates that, while we may be a nation of tea-drinkers, we are not knowledgeable about speciality teas. 'We sell about 400 different teas,' says the manager, Mustapha Abdedaim, modestly pointing out that the Chinese identify 2,000 possible types. 'We certainly do not know of any bigger choice of teas in France, but the number of teas is not in itself enough. We choose the rarest teas, those that are the best representatives of their type, and the most interesting ones.'

Scan the Darjeeling section, for example, and you appreciate what he means. There are no fewer than 18 different 'first-flush' (the first and most delicate spring growth) types of Darjeeling, prized for its flowery aromas of muscat grape and green almonds. These represent the pick of the Darjeeling region's top tea gardens. There is Castleton SFTGFOP1 (Special Finest Tippy Golden Flowery Orange Pekoe, 1st quality), growers' shorthand for the part of the tea bush that has been picked. Castleton is legendary among the area's distinguished gardens for its sublime perfume.

It is a sublime price, too, at pounds 24 for 100g; but there are cheaper first flushes, with Bloomfield and Lingia (both SFTGFOP1) offering exceptional high-altitude flavours and scents at pounds 15. Still within the first-flush category, there is a garden such as Soureni (a 'BPS': Broken Pekoe Souchong) where the vigorous lower leaves have been picked - a decent drink from the foothills of the Himalayas for a more affordable pounds 4.50.

First flush over, move on to a solitary 'in-between' picking from Seeyok tea garden. This retains the famous flowery scent, but shows more of the body to come in the further 21 'second-flush' teas. These are picked in the summer, when the tea bushes are showing more vigorous growth, and are prized by tea enthusiasts for their ripe fruit flavours and more rounded and vigorous strength. The second flush teas are not just repetitions. Though some gardens appear on both lists, such as Castleton, the majority do not.

Pride of place among second flushes goes to Jungpana, also a SFTGPOP1, whose fruity-hazelnut flavours cost pounds 30 for 100g.

That is just the Darjeelings. If you want Nuwara Eliya, the classiest Sri Lankan tea, there are five different tea gardens to choose from. And, from Assam, there is another lengthy choice of first and second flushes. Ask for a smoky tea, and you can sniff through pine-smoked Lapsang Souchong Imperial, Grand Lapsang, plain Lapsang, and Terry Souchong, all from China's Fujian province, and then inhale other perfumed teas such as Mariage's Smoky Earl Grey, or another house blend, Zsar Alexandre.

While we are used to one jasmine tea, there are 10 on offer here, from Jasmine Monkey King to Jasmine Mandarin Oolong.

Talk green (non-fermented) and you are looking at 34 Chinese types - and that is before you look to Japan, where you will find another 17, including Gyokuro, perhaps the most precious tea in the world. For three weeks before harvest, this tea garden is covered with black curtains so that it offers the maximum chlorophyll and the minimum tannin. At pounds 60 for 100g, it is only marginally more expensive than Yin Zen (translated as 'silver needles'), a rare 'white' tea, so-called because of the silver-white buds that are picked entirely by hand.

These elite teas are supported by an impressive cast of interesting but cheaper teas, and countries are represented that you never see in Britain. From pounds 2.40 to pounds 3, for example, you can taste your way through the 'red' teas of South Africa. Brick- coloured, with tiny, grassy leaves, these are naturally free of theine (the tea equivalent of caffeine) and, once brewed, exude the most extraordinary scent of Bourbon vanilla, although none has been added. There are Russian, Latin American, Australian, Papua New Guinean, Nepalese, Vietnamese, Turkish, Mauritian and Korean teas, all selected by Mariage's chief buyer, Kittichat Sangmanee, who sources the teas with the help of a worldwide chain of agents.

Add to that the less-classic perfumed teas which are now in vogue. First come the fruit and floral flavours, black tea perfumed with natural aromas as diverse as bitter orange, rhubarb, violet and ylang-ylang; then the house blends with such mysterious names as Kabuki, Aida and Balthazar. The blend of the moment is Marco Polo, which smells lightly of vanilla and caramel with a hint of strawberries. That may sound disgusting, but it is delicious: no wonder 'le tout Paris' regards it as 'le must'.

The shop is beautiful, aromatic with the teas which are stored in black tins on aged shelves, all part of an immaculately maintained colonial setting, dotted with antique tea paraphernalia. There is a tea museum upstairs and an inner courtyard under a glass verriere provides a restaurant.

The only way to cope with the choice in Mariage is to write off a couple of hours, sniff through the teas, listen to the staff and immerse yourself in the ambience. Do not take any more money than you want to spend. The teas are endless, the equipment stylish - Art Deco teapots with integral filters, non- chlorine-bleached tea strainers, all the kit for a Japanese tea ceremony. The temptation to spend is overwhelming.

Mariage is also keen on explaining the ritual of tea-making. This includes a chart which shows the amount of tea needed for a quantity of water (the French regularly overdose, says Mr Abdedaim), the temperature of the water, and the number of minutes (wildly different) that various teas should be allowed to brew before the leaves are removed to prevent bitterness.

The gospel according to Mariage dictates that tap water is out (too chlorinated, too limey), and that bottled mineral water (preferably from a mountain source) is de rigueur. Sugar is discouraged unless it is the candy type (white and neutral in flavour). Lemon is always off-limits, since it is considered too acid (substitute orange if you must). Teabags are acceptable in theory, as long as they are not bleached with chlorine (which affects the tea's taste) and the content is top quality. Mariage stocks only five types of house teabags, a reflection that they are still a slight deviation from the serious business of tea-drinking.

A tiny quantity of milk is tolerated in more full-bodied African and Sri Lankan teas; but in a delicate Oolong, exclaims Mr Abdedaim in a shocked tone, it would be 'un crime'.

Mariage Freres, 30 rue du Bourg-Tibourg, Paris 4eme, (and 13 rue des Grands-Augustins, 6eme). Mail order: telephone (010 33 1) 40 09 81 18 or fax 40 09 88 15.

(Photograph omitted)