If you’ve been paying attention to the colour of the back bar in your local pub, or the microtrends of #ginstagram, you might have noticed something peculiar. Gin has turned purple. Or, more precisely, violet. Coloured gins are having a moment, the latest phase in the great craft gin revival. You can now choose from a whole spectrum, including pink grapefruit gin, Amalfi lemon gin the colour of a pale sunrise, bitter orange gin like alcoholic marmalade and lavender gins that change colour on contact with tonic. But the most popular is violet.

Violets grow like weeds, pretty much everywhere. The sweet, perfumed kind, Viola odorata, is a southern French speciality, while the parma violet, Viola alba, was first cultivated in Italy in the 16th century. The taste is natural, but tastes unnatural, a bit like biting off a shard of rainbow or licking a My Little Pony. You might associate it with grandmothers, soap or those cheap Parma Violet sweets made by Swizzles of Derbyshire, which occasionally turned up in 1980s party bags.

The ancient Greeks cultivated violets and the Romans couldn’t get enough violet-scented wine. The word violet comes via the nymph Io, mistress of Zeus, who hid her from his wife, Hera, by turning Io into a cow. Io kept crying, so he turned her tears into violets so she’d have something nice to eat besides grass. Until the 19th century, it was the violet not the rose, that signified love.

How fitting, then, that the more recent violet wave crested on Valentine’s Day 2018, when the Sweet Violet gin liqueur made by Manchester distillery Zymurgorium went viral on Instagram. For a while, it was the best-selling liqueur on Amazon. Since then, pretty much every British supermarket from Aldi to Asda has brought out its own version and violet has transferred to non-gin categories. The Artisan Drinks Co makes a violet blossom tonic. Brothers just brought out a parma violet cider.

Halewood is one distiller that has managed to stay ahead of the trend. Its Whitley Neill Parma Violet Gin and JJ Whitley Violet Gin together make up 90 per cent of violet trend sales off-trade (ie, for home drinkers). “London dry gins were having a resurgence, but now our flavoured gins have completely taken the category by storm,” says Ms Leanne Ward, who manages the brands. “The demographics are completely different. People are getting into flavoured gin who completely bypassed regular gin.”

Violet has never been out of its top five bestsellers. The colour is clearly important. Whitley Neill’s liquid is transparent, as you’d expect for a distilled product, but it does come in a violet bottle. “There are so many bottles on those gin shelves now, the question is, how do you stand out?” asks Ms Ward. “You’ve really got to do something different. There’s a romance with violet. It’s intriguing. It’s different. You don’t know exactly what it’s going to be like. I don’t want to allude to the sweets exactly, but it might have that retrospective appeal. Then there’s a huge trend towards florals in cocktails in recent years.”

It wasn’t so long ago that violet was one of the great “lost” flavours: crème de violette was one of those antique ingredients that showed up all the time in classic cocktail books, but you couldn’t find it for love nor money. Violet was also the key ingredient in a Parfait Amour, sickly-sweet love potion-type liqueurs that were wildly popular in the 19th century and Crème Yvette, a proprietary berry liqueur distilled in Philadelphia until 1969.

A few years back, if you wanted to make a classic Aviation (see below), as listed in Mr Hugo R Ensslin’s Recipes For Mixed Drinks (1916), you’d have to go to great lengths – or maybe just southern France – to source the crème de violette that lends the cocktail its sky-blue tinge. In his Savoy Cocktail Book (1930), Mr Harry Craddock omitted the violette. Presumably it was hard to come by even then.

The gap was filled by Rothman & Winter, which created an alpine-style crème de violette in the US, and by the excellent German distillery The Bitter Truth, whose Violet Liqueur (“its colour is reminiscent of a full moon reflected on a river in the twilight”) was aimed precisely at craft bartenders. Now there are more crème de violettes than you can shake a stick at. There’s even a revived Creme Yvette for your Blue Moons. Many of the violet “gins”, it should be added, are really liqueurs as opposed to gins, with sugar and colour added after distillation.

When used subtly, violet can be a delight. Ms Hilary Whitney, who makes Sacred gin, notes its similarity with orris root, a key ingredient in gin. Orris is made from the bulbs of irises, which are peeled and left to dry and mature before being ground into a powder and added to gin as a fixative. “It has been described as the olfactory equivalent of the colour purple,” she says. “A useful way of understanding this is to think that making gin is a bit like building a house. The botanicals are the bricks and orris is the mortar that binds them together.” Sacred’s orris gin makes a particularly excellent Aviation.

What’s at the source of our new-found love of violet? “Instagram has massively speeded up the trend process,” says Ms Kristy Sherry of the online retailer Master of Malt. She often has to respond to sudden microspikes in demand when a particular product trends on social media. “In the past, these trends were driven by young people living in cities. Now older people in the suburbs are also looking for Instagrammable drinks.”

All the same, her data show that violet may have already peaked. “To be honest, we found that 2018 was the year of violet,” she says. “The Zymurgorium brand caused a huge spike. The biggest month we had was July 2018. We had a good long tail, but it’s not a trending product any more.” She says we should watch out instead for mead, vermouth, pineapple-spiced rum and orange gin. “We think that’s going to be huge,” she says, much in the same way a record label might have touted a hot new act in the past.

“If you think about the number of gins that are being launched, we’re nowhere near peak gin. Gin is still up. Volumes are still enormous. It’s just that people are constantly looking for the new thing now.”

The Aviation is not so much about the violette as the maraschino liqueur, which is what lends the sweetness. Luxardo makes the best. The violet is really there for colour and a slight faraway note. A gin-based violet liqueur will work just as well as French-style crème de violette. Or you could simply use unsweetened violet gin as the base and omit the extra liqueur.

• 50ml gin
• 15ml maraschino liqueur
• 15ml lemon juice
• 5-10ml violet liqueur

Shake all the ingredients over plenty of ice and fine-strain into a frozen glass.

Garnish with a cocktail cherry.