Jack reached into his pocket, ‘accidently’ taking out the fake Bentley key ring. Once he was certain that Betina had seen both the keyring and the fake Rolex, he replaced the keys and dipped into his right-hand pocket. From here, he removed a folded page from Vogue magazine showing a ring – a large square-cut emerald, surrounded by diamonds, on a platinum band.

Betina looked at it appreciatively. ‘Your girlfriend clearly has wonderful taste. Are you specifically looking for an emerald? We have a lovely range of rose diamonds in at the moment. And is her heart set on the square-cut, do you know? It’s the most common, of course, but . . . if she’s as special as you suggest, perhaps “common” isn’t the way to go.’

Jack shook his head. ‘Emerald is her birth stone, so nothing else will do. The square-cut isn’t important as long as it’s around three carats.’ Jack continued to talk breezily about jewellery that cost about a third of his annual police salary and began to enjoy the feeling of power it gave him, knowing that Betina totally believed in the fake persona he’d created. When another customer entered the shop, Betina called the young woman from behind the counter to deal with him so she could focus on Jack.

Now that Betina had an idea of Jack’s girlfriend’s taste, she asked about the special occasion he’d mentioned. This was the question Jack had been waiting for. ‘It’s to celebrate one of her Arabians winning a European title.’

There was a brief glint of interest in Betina’s eyes, but she clearly didn’t want to be diverted from a potentially big sale onto the subject of horses. ‘I’d estimate the ring in Vogue to be priced at around fifteen to twenty thousand pounds. Is that roughly what you expected?’

Jack laughed softly. ‘That’s a little less than I thought you’d say, actually.’

Betina smiled, as if money was of no importance to either of them. ‘We have several rings I think you might want to look at. They won’t be identical, of course. We have a couple of the rarer, round emeralds, and we have two five-carat examples that I can show you. We also have some vintage styles. Would you like to see those as well?’

‘I’m happy to put myself in your very capable hands,’ Jack smiled back. As Betina turned to open the office door, the bell above the door rang and the other customer left, letting someone else in at the same time. A deep, velvety voice quickly echoed around the small shop.