'It would be far worse if you all fell out,' he said, 'and weren't speaking at all. In your case, a full-on soul-baring confrontation may not be worth the effort in the long run. You have two parents and they f.u.c.ked up but they must have done something right because your outlook on love and marriage is so utterly positive.'

While Petra considered Arlo's words, she swung her legs absent-mindedly, catching her foot each time on a plastic pirate ship run aground on the gra.s.s.

'What hampers you from accepting your relationship with your folks for what it is, is that you know too much,' Arlo said, 'but they don't know that. And they mightn't be the most warm or loving of parents but I bet you anything they'd be horrified if they knew that you knew. Remember that wasn't their intention. It's an age-old thing, isn't it cringing at the thought of one's parents making love. But actually seeing one's parents having group s.e.x well, that's off the b.l.o.o.d.y radar. What they got up to it wasn't depraved, but there again it wasn't particularly wholesome. It was, however, private and consensual.' He gave Petra time to consider this, waited for her to nod. 'But in the long run, it wreaked havoc with their lives. And the cause and the effect have been with you practically your whole life, Petra.'

'It may have been what split them up, you know,' Petra said. 'I've read articles about similar situations wife-swapping and threesomes usually come to grief.'

Arlo looked at her. 'd.a.m.n,' he said, 'and Nige and I were talking just the other day about whether you and Jenn would be up for it.' Petra glared at him for a split second before a mischievous grin sliced the gorgeous dimples into his cheeks. She thumped him. And he hugged her.

'What's going on out here?' John asked, coming into the garden with hastily made sandwiches.

'Did you know that your daughter is the buzz-word in contemporary jewellery design, from Hatton Garden to Hollywood, Mr Flint?'

'No,' said John, who hadn't yet said to Arlo, Call me John.

'She's in demand by the great and G.o.dly of stage, screen and beyond.'

'Really?'

Petra didn't think she'd mention Mrs McNeil to her father because she couldn't remember whether or not he knew about her at the time. She thought he probably did not. Instead, she rifled through her bag and brought out one of the final sketches for the tanzanite bangle. She'd slipped it in this morning. Just in case the opportunity arose.

John looked at it. 'This is marvellous,' he said and he looked at Petra and she saw that actually, he looked rather proud.

Although Petra couldn't quite commit to leaving London completely by the start of term a month later, she did give up her flat. It wasn't much of a sacrifice; she never felt particularly emotionally attached to it. And anyway, Eric had gone to great lengths to a.s.sure her that she was more than welcome to lodge with him. Similarly, in Yarm, Jenn had given Petra a set of keys to her flat with a pink satin ribbon attached. Come and go as you please, they both told her.

So it was back to school in September. Petra missed Arlo inordinately that first week; their reunion at the weekend was sweet and intense. And though she was tempted to stay the following week with Jenn, she had so much work on that she was compelled to return to London. Charlton would be taking a reasonable cut for himself for the first two bracelets he had secured for her yet it had been his suggestion that she set up her own website and Gina's husband was helping her do so.

'We'll make this your virtual gallery,' he told her and the concept did get her mind ticking. Orders for her earrings, the hair slides and crocheted necklaces soon started to trickle through. And one day, after a lengthy period spent on spreadsheets, Petra typed in 'jewellers studios workshops Yorkshire' into an Internet search engine and was quite surprised by what came up. She was suddenly aware that Eric was looking over her shoulder. She fumbled around trying to minimize the page but Eric stilled his hand over hers, over the mouse.

'It's OK, Petra,' he said and he smiled. 'All of it is OK.'

And she knew Eric was right. She thought to herself how lucky she was. From London to Hong Kong via Yorkshire, the world wasn't such a big place really, not when it was one so full of friends.

The bracelet was finished. It was all Petra had hoped it would be. She felt euphoric. She had it professionally photographed from every angle. Kitty and Eric heaped their praises on her and Gina brought in champagne.

Charlton informed her that the actress would be coming in a fortnight.

'Now it's full steam ahead with the emerald one,' Petra laughed.

Once Petra knew that the money was in transit, something inside her changed. It was subtle at first. She went from looking at the work a few times a day to having a glance only every now and then, to not taking it out of the box at all. Everyone sensed there was something troubling her but she didn't let anyone probe because she wasn't entirely sure herself what it was that irked her so.

Up in Yorkshire for the weekend, she rose from her sleep. She walked away from Arlo's bedroom and through the lounge into the kitchenette. She didn't switch the lights on; fumbling with the lid of the kettle in the dark, filling it with water which splashed everywhere. She set it to boil. Took a mug, a tea bag, poured milk without spilling a drop.

She sat, in the dark, on Arlo's sofa.

'I don't think this is what you'd want,' she said quietly. And she said it over and over again.

Petra wasn't sleepwalking. She was wide awake.

She wasn't sure how long she'd sat there for but when she returned to the bedroom with cold feet and the start of a headache, she clocked the time was nearing half four. She put on a pair of Arlo's socks and slid into bed, cuddled up against his back.

'Are you awake?'

He wasn't.

'Are you awake?' she said a little louder, nudging his body. 'Are you awake?'

'I am now,' he said groggily.

'I can't do it,' she said and her voice shook.

He turned towards her. Her eyes accustomed to the dark, she could see his focusing intently on her. 'Can't what, Miss Flint. What can't you do?'

'I can't do it, Arlo,' she said. 'I can't let Mrs McNeil's tanzanite go. Not in that bracelet. Not to the United States.'

She dreaded telling Charlton. The actress was flying in on Friday. When Petra's feet finally dragged her from the studio to the Charlton Squire Gallery late on the Monday afternoon, she felt ill.

'You look peaky, darling,' Charlton said. 'Everything OK?'

'No,' Petra whispered, 'it isn't.' Charlton seemed huge today, top to toe in black, a diamond-encrusted skull and crossbones dangling from a choker around his neck.

She clambered over her words, leaving sentences hanging vertiginously. Charlton listened intently and then, after a nauseating silence during which her head started spinning, he began to laugh.

'I was wondering when you were going to say that,' he said. 'I'm amazed it took until now.'

'Sorry?' Petra's head stopped spinning but she couldn't keep her eyes still; they were scouring Charlton's face in confusion.

'Darling, as soon as I saw your design on paper let alone in metal with that f.u.c.king sweet I started rearguard action.'

'What?'

'Plan B, Pet, Plan B.' He paused. 'It's Monday. I need to make a call. Excuse me for a moment.'

He disappeared into his office leaving Petra to man the shop and by the time Charlton came back, she'd sold a pair of her own earrings and one of Charlton's belt buckles.

'You need to meet me at Oxford Circus tube station, ten o'clock tomorrow morning,' he told her. 'And bring the bracelet.'

Neither Arlo nor any of the Studio Three could help Petra work out what was at Oxford Circus tube station.

Charlton led Petra a little way down Regent Street before turning down a side-street. He rang the top bell of a small office. He and Petra were buzzed through and climbed steeply to the top floor. The office s.p.a.ce was cramped because most of the room was taken up by a large cage, in which were a number of safes. Two young women sat sharing a desk.

'Hi, Charlton,' they said.

'This is Petra Flint,' he introduced. He turned to Petra. 'This lady represents one of the few companies left mining for tanzanite. And this lady is from the foundation which ensures ethical mining and fair-trade initiatives.'

'We hear you have something to show us,' she said, eyeing Petra's bag.

'Charlton told us it'll blow our brains,' said the other.

Not quite knowing what any of this was about, Petra took the box from her bag and let the women inspect her bracelet. 'It's a beauty!'

'Stunning!' It didn't take Petra long to realize their primary focus was on the stone and not the whole.

'Can you match it?' Charlton asked.

'Don't be ridiculous, Charlton,' said the first woman. 'It's tanzanite. Of course we can't match it. But we'll have something comparable.' She unlocked the cage, opened a safe and brought out a few white leather purses. Each contained a sizeable stone. 'But you may have to go for a different cut,' she told Petra, almost apologetically. 'And of course you'll also need to rework the housing to accommodate a new stone. We can find a similar weight but the colour of yours, it's truly exceptional. We won't have anything that blue. Tell me more about it how did you come by it? Have you had it graded?'

'I've had it for over sixteen years. It was bequeathed to me by a lady whose husband was a prospector in Tanzania in the 1960s he was looking for rubies at the time because of course no one knew of the existence of tanzanite. So, no one else has had this stone. I believe it's vBE, eye-clean. 39.43 carats.'

'Wow.'

'Double wow,' said the other woman. She grinned at Petra. 'And it's definitely not for sale?'

Petra laughed and shook her head. 'Nope. Never.'

So Petra didn't make her fortune from that first bracelet because she had to balance the profit against the purchase of a new stone. In the end, the actress came away with just over 40 carats of tanzanite which in her reckoning was preferable to just under. Even if the cut was not as mesmerizing as Petra's and the new stone was a touch more violet than blue. It was still dazzling. Just not quite the colour of dreams.

Epilogue.

Did Petra Flint sleepwalk again? Occasionally, but Arlo would watch her leave the bed and mostly she would just hover by the bedroom door before retracing her steps and coming back to sleep.

And did Arlo Savidge's insomnia disappear? Not entirely, certainly not overnight, but it subsided significantly. And if there were nights when he couldn't sleep, he found that gazing at his girlfriend was far more soothing than staring at marks on the paintwork. There was nothing specific keeping him awake any more, just a hard habit he was slowly learning to break. And if things go b.u.mp in the night then he wakes up and guides her back to bed.

He kept her secret and she kept his and they found in each other a place of such safekeeping that they knew any future issues or grievances, on whatever scale, could be dealt with together. Custodians of each other's hearts.

'Ah, the return of the native,' Kitty greeted Petra after a fortnight's absence up north.

'How are you, Kitty,' Petra gave her a fond hug.

'One of these days I'm going to surprise you, Petra. I'm going to jump on a train and spring a visit. All this talk of looking for a studio and finding inspiration in the landscape. I bet I'd find you sprawled on Jenn's sofa watching daytime TV.'

Petra laughed. And then she thought about it. 'Why don't you come up and visit, Kitty? I'll take you to Whitby. You'd love it. Goths and amazing jet and fantastic chips too. Please come.'

Kitty returned to her bench but the look on her face told Petra she was actively considering the invitation. 'Maybe.'

'Name your date!' Petra laughed, excited.

'Next month perhaps? Otherwise it'll have to wait until after Christmas.'

'Oh Kitty, please come.'

'How long are you down for this time?' Gina asked, bringing over a cup of coffee.

'A couple of weeks, actually. I need to get cracking on the bracelet with the three rubies. Where's Eric?'

'Said he'd be in by lunch-time.'

Petra's mobile phone bleeped through a message. 'That'll be him now, probably.'

Mum says pls come 4 xmas Petra looked at the message and frowned. Who on earth was this? She didn't recognize the number. Was it Tinks, her mother's barking friend? It couldn't be her father, that would make no sense at all. She sent a message back.

Who is this?

There was no reply. Must be the text equivalent of a crossed line, Petra thought to herself. She deleted the message and thought no more of it until her phone bleeped again over an hour later.

It's me For Christ's sake.

Who's me?

Another interminable wait. Petra was starting to feel irritated.

Arlo u mad woman who did u think it was?

Petra's fingers felt all thumbs as she tried to scroll through the options on the message to have the number called back instead of replied to by text.

'Hullo?' said Arlo's voice as if he didn't have a clue who'd be ringing him at this time. He was walking between lessons and was eager not to let the boys see him practising what the school preached against during school hours.

'Arlo? It's me. Whose phone is this?'

'It's mine.' He sounded quite put out.

'But you don't have a mobile phone.'

'I do. As of today.'

'But why did you get one?'

There was a pause.

'Because I miss you.' He paused again. 'I miss you when you're not here.'

Petra was in too much of a swoon to be able to answer him.

'Anyway, Mum wanted to know if you'd like to come for Christmas?'

'I'd love to,' said Petra.

'Shall I text her or will you?' Arlo asked.