Who'd spend pounds 300,000 on a necklace?

Laura Tennant goes shopping on the scary side of Bond Street

Chanel's first "serious" (ie bloody expensive) jewellery shop is not the kind of place you just saunter into. Loitering outside, you'll catch glimpses of lacquered chinoiserie, taupe suede and, of course, case after case of clunky, chunky, platinum and gold, encrusted with pearls, diamonds, sapphires, rubies... Restraint, we can safely say, is not the keynote of Chanel's new jewellery collection, launched earlier this month.

If you pluck up the courage to ring the buzzer, a tall young man trying very hard to speak with a posh voice will admit you (you'll find that even in your best jacket, you feel urchin-like). Once inside, if you're not blinded by the glare of millions of pounds worth of girl's best friends, you may be dimly aware of someone of the billionaire class calmly discussing the carat of the large rock-like object in his hands.

If the only way you could ever buy even one half of a pair of Chanel earrings is by winning the Lottery, I challenge you to spend longer than a minute in this shop. After the first 30 seconds, you will start to feel dizzy and your breathing will become laboured. Full-blown altitude sickness will hit after 60 seconds and I'd advise you to get out, fast. Such places are not for the likes of us.

The super-rich, however, are a different matter. Bond Street doesn't even begin to soak up their vast wealth, and if you're super-rich, what else is there to do except shop? The joy of the designer label is Mark Up, and if you can charge around pounds 300 for a white T-shirt (remove pearl buttons before handwashing), just think what you can ask for a necklace (pounds 300,000, as it happens). The final irony is that in the microeconomy of the billionaire, the more expensive something is, the more valuable it is (go figure). That means the more they pay, the more they enjoy.

So, pity the super-rich with no taste, who haven't realised that, all too often, the pricier something is the nastier it is. While normal people press their noses against the shop-front of Nicole Farhi, they are drawn like magpies to the windows with the brightest colours and biggest buttons. And what better to go with that overpriced fuschia suit than a glittery, conspicuous brooch from Chanel?