Ripley Under Water contains too many Derwatt references to quote them all in full. I will therefore summarise the contents with direct quotes of the most important passages.

Tom establishes the timeframe of this the last Ripley novel by noting that his income from Derwatt products has obviously reduced in the five years since Bernard Tufts’s suicide.

Tom’s thoughts while discussing Cynthia (Bernard’s girlfriend) with the Pritchards state Cynthia’s full knowledge and profound disapproval of the forgeries and the possibility that she might publicise what had been going on,

That was a can of worms, if the Pritchards or anybody else – especially Cynthia Gradnor, who knew as well as the Buckmaster Gallery people that the last sixty-odd ‘Derwatts’ were forgeries [3] – ever opened it, and told the truth. No use trying to put the lid back on, because all those very expensive paintings would become next to worthless, except for eccentric collectors who were amused by good forgeries; like Tom, in fact, but how many people in the world were like him, with a cynical attitude
towards justice and veracity?
… Tom also remembered that Cynthia detested him because Tom had though up the idea of Bernard Tufts’s forging Derwatts, after Derwatt’s suicide. Bernard had done the forgeries brilliantly and successfully, working slowly and steadily in his little London Garret-cum-studio, but he had ruined his life in the process, because he had adored and respected Derwatt and his work, and had finally felt that he had betrayed Derwatt unforgivably. Bernard had committed suicide, a nervous wreck.
Tom was not going to say anything about Jeff Constant, a photographer, and Ed Banbury, a freelance journalist, who years ago had bought the Buckmaster Gallery on the strength of Bernard Tufts’s forgeries and the profit they would derive from them. Tom was also deriving a percentage from Derwatt sales, a sum merely steady in recent years, but that was normal considering no more forgeries were coming since Bernard Tufts’s death.
Bernard’s conscience had not been able to bear the weight of his guilt in creating sixty or seventy paintings and countless drawings over the years.

Tom notes that while he does not know which work was Bernard’s first forgery or precisely when it was done, Cynthia might.

While Heloise is taking a harpsichord lesson, Tom contemplates his Derwatts (or Tufts)
He lit a cigarette, stood behind the long sofa, and gazed at the Derwatt over the fireplace. Not a Derwatt, Tom reminded himself, but a Bernard Tufts forgery called ‘Man in Chair’ . It was reddish-brown with some yellow streaks, and like all Derwatts, had multiple outlines, often with darker strokes, which some people said gave them headaches; from a distance the images seemed lifelike, even slightly moving. The man in the chair had a brownish, apelike face, with an expression that could be described as thoughtful, but was by no means defined by clear-cut features. It was the restless (even in a chair), doubting, troubled mood of it which pleased Tom; that and the fact that it was a phoney. It had a place of honour in his house. [U1]
The other Derwatt in the living-room was ‘The Red Chairs’, another medium-large canvas, of two small girls about ten years old, sitting on straight chairs in tense attitudes, with wide, frightened eyes. Again the reddish-yellow outlines of chairs and figures were tripled and quadrupled, and after a few seconds (Tom always thought, imagining a first view) the viewer realised that the background could be flames, that the chairs might be on fire. What was that picture worth now? A six-figure sum in pounds, a high six-figure. Maybe more. It depended on who was auctioning it. Tom’s insurer was always upping his two paintings. Tom had no intention of selling them. [V1]
If the vulgar David Pritchard managed to blow all the forgeries, he could never touch ‘The Red Chairs’, of course, whose provenance was old and from London. Pritchard couldn’t  stick his clumsy nose in an cause devastation, Tom thought. Pritchard had never heard of Bernard Tufts. The lovely measures of Franz Schubert gave Tom strength and heart, even though Heloise’s playing was not of concert standard; the intention, the respect for Schubert, was there, just as in Derwatt’s – no Bernard Tufts’s  ‘Man in Chair’ the respect for Derwatt had been there when Bernard painted it in Derwatt’s style.
Tom relaxed his shoulders, flexed his fingers and looked at his nails. All neat and proper. Bernard Tufts had never wanted to share in the profits, in the rising income of the false Derwatts, Tom recalled. Bernard had always accepted just enough to keep himself going in his studio in London.
If a type like Pritchard exposed the forgeries – how? – Bernard Tufts would be exposed, Tom supposed, dead though he was. Jeff Constant and Ed Banbury would have to answer the question, who had been forging, and of course Cynthia Gradnor knew. The interesting question was, would she have enough respect for her former love Bernard Tufts not to betray him by name? Tom felt a curious and proud desire to do just that, protect the idealistic and childlike Bernard, who had finally died by his own hand (or action, jumping off a cliff in Salzburg) for his sins.
Tom’s story had been that Bernard had left his dufflebag with Tom while he, Bernard, went off to look for a hotel room, as he wanted to change his hotel; and Bernard had never come back. In truth, Tom had followed Bernard, who had jumped off a cliff. And Tom had cremated the body the next day, as best he could, and claimed that the body had been that of Derwatt. And Tom had been believed.

Tom flies to London and stays with Ed.
Ed and Jeff and Bernard, but especially Bernard, had been friendly with Derwatt the painter. And when Derwatt, in a depressed period, had gone off to Greece and deliberately drowned himself off some island there, the friends back in London had been understandably shocked, bewildered: in fact, Derwatt had merely ‘disappeared’ in Greece, because his corpse had never been found. Derwatt had been around forty, [4] Tom thought, beginning to be recognised as a painter of the first category, with presumably his best work ahead of him. Tom had come up with the idea of Bernard Tufts, the painter, trying some Derwatt forgeries.

Tom and Ed visit the Buckmaster Gallery where Nick Hall is the new salesperson.
A taxi to Old Bond Street, to the discreetly lighted, brass and dark-wood framed window of the Buckmaster Gallery. The fine old door still had its polished brass handle, Tom noted. A couple of palms in pots in the front window flanked an old painting and concealed much of the room beyond.

Ed introduces Tom to Nick and says that he wants to view some paintings.
‘We have six Derwatts just now, sir, ‘ said Nick
… Nick showed the Derwatts by placing them on a chair seat and letting them lean against the back. The canvases were all Bernard Tufts, two Tom remembered, four he did not. ‘Cat in Afternoon’ pleased Tom most, a warm reddish-brown and nearly abstract composition in which a marmalade-and-white cat was not at once findable, a sleeping cat [W1]. Then ‘Station Nowhere’ , a lovely canvas of blue, brown, tan spots with a chalky but dirty-looking building in the background, the railway station, presumably [X1]. Then – people again – ‘Sisters in an Argument’ , which was a typical Derwatt, though to Tom a Bernard Tufts because of the date: a portrait of two females facing each other, mouths open. Derwatt’s multi-lined outlines conveyed a sense of activity, noise of voices, and the dashes of red – a favourite devise of Derwatt and copied by Bernard Tufts – suggested anger, maybe the scratching of fingernails and the blood therefrom. [Y1]
‘And what are you asking for this?’
‘”The Sisters” – close to three hundred thousand, I believe, sir. I could check it. Then – if a sale is near, I am to notify one or two other people. That’s a popular one.’ Nick smiled again.
Tom wouldn’t have wanted it in his house, but he had asked the price out of curiosity. ‘And the “Cat”?’
‘A little more. That’s popular. We’ll get it.’
… Tom nodded thoughtfully. ‘I like the “Cat”. Whether I can afford it or not – I’ll to think about it.’
‘You have – ‘ Nick seemed to try to recollect.
‘Two,’ Tom said. ‘”Man in Chair” – my favouritr – and “The Red Chairs”.’

Back at Ed’s flat, they discuss the ‘disappearance’ of Murchison and his forged Derwatt The Clock, but no further details of the painting are given. Then,
Tom was thinking of the early days when Jeff had made the excellent photographs of Derwatt (genuine) paintings, and Ed Banbury had talked them up, had written articles on Derwatt, carefully dropped a word here and there that would start the publicity ball rolling, they had hoped, and the ball had started rolling. Derwatt had been living in Mexico was the story, still lived there but was a recluse, refused interviews, and refused even to tell the name of the village where he lived, though it was believed to be near Veracruz, from which port he shipped his paintings to London. The former owners of the Buckmaster Gallery had been handling Derwatt without impressive success, because they hadn’t tried to push him.  Jeff and Ed had done that only after Derwatt had gone to Greece and drowned himself. They had all known Derwatt (all except Tom, curiously, though Tom often felt as though he had  known him). Before his death, Derwatt had been a good and interesting painter, ever on the edge of poverty in London, an admired acquaintance of Jeff and Ed and Cynthia and Bernard. Derwatt was from some dreary northern industrial town, Tom forgot which. It was the talking up that had done it, Tom realised. Curious. But then Van Gough had suffered from the lack of talking up. Who had talked Vincent up? No one, maybe only Theo.

Tom returns to the Gallery.
‘Have you any drawings of Derwatt that I could see?’
Nick hesitated briefly. ‘Y-yes, sir. They’re in portfolios in the  back room. Mostly not for sale. I think none is for sale – oficially.’
Good, Tom thought. Sacred archives, sketched for paintings that had become classics, or would have become. ‘But – is it possible?’
‘Sure. Certainly, sir.’
… Nick squatted and lifted a portfolio. ‘About half of these are sketches for paintings,’ he said, holding the big grey portfolio in both hands.
There was an extra table near the door, and Nick laid the portfolio reverently on it and untied the three strings that closed it.
‘More portfolios are in the drawers here, I know,’ Nick said
…Each Derwatt drawing was in a transparent plastic envelope. Charcoal, pencil and conte. As Nick lifted one after the other, all in their plastic, Tom realised that he could not tell the Derwatts from the Bernard Tufts, not with total confidence, anyway. ‘The Red Chairs’ sketches (three), yes, because he knew that was a Derwatt creation. But when Nick came to the ‘Man in Chair’ preparatory sketches, a Bernard Tufts forgery, Tom’s heart gave a leap, because he owned the painting and loved it and knew it well, and because the devoted Bernard Tufts had done his preparatory sketches with the same loving care as would Derwatt. And in these sketches, made to impress no one, Bernard had been fortifying himself for his real effort, the composition in colour on canvas.
‘Do you sell these?’ Tom asked.
‘No. Well – Mr Banbury and Mr Constant don’t want to. As far as I know we’ve never sold any. Not many people – ‘ Nick hesitated. ‘You see, the paper Derwatt used – it wasn’t always of the best quality. It gets yellow, crumbles at the edges.’
‘I think they’re marvellous,’ Tom said. ‘Keep on taking care of them. Out of the light and all that.’
… There were more. ‘Sleeping Cat’ which Tom liked, done by Bernard Tufts (Tom thought), on rather cheap good-sized sheets, with colour indications in pencil: black, brown, yellow, red, even green.
It occurred to Tom that the Tufts blended so well with Derwatt that it was artistically impossible to separate them, at least in some or most of these drawings. Bernard Tufts had become Derwatt, in more senses than one. Bernard had died in a state of confusion and shame because of his success, in fact, in becoming Derwatt, in Derwatt’s old lifestyle, in his painting, and in his exploratory drawings. In Bernard’s efforts, at least those here in the Buckmaster Gallery, there was no sign of faint-heartedness in Bernard’s pencil or colour pencil sketches. Bernard appeared the master of the composition in question, and decision about proportion and colour.
… ‘What would the gallery ask for a preliminary drawing – for one of the paintings?’ … ‘I couldn’t say sir. I really couldn’t. I don’t think I’ve got the drawing prices anywhere here – if they exist.’
Tom swallowed. Many, most of the drawings came from Bernard Tuft’s modest little studio somewhere in London, where he had worked and slept in the last years of his life. Oddly, the sketches were the best guarantee of authenticity of Derwatt’s paintings and sketches, Tom thought, because the sketches betrayed no change in the use of colour, which Murchison had been so hung up on.
… [Tom thought after leaving the store] if Derwatt was ‘exposed’ as having been forged for the bulk of his work, what would it matter, since Bernard Tufts’s efforts had been equally good, absolutely similar and logical, had shown the same development that the real Derwatt night have shown if he had died at fifty or fifty-five instead of thirty-eight, or however old he was when he had committed suicide? Tufts, it could be argued, had improved upon Derwatt’s earlier work. If the sixty percent (Tom estimated) of Derwatt works now extant were to be signed B. Tufts, why would they be less valuable? [4]

Tom finds Cynthia’s workplace and persuades her to go for a drink where he tries to persuade her to co-operate with the fraud.
…’Bernard was at this for so long – six, seven years? – that he developed and improved – and in a way became Derwatt.’

… Tom persisted. ‘More important – what would the catastrophe be, if the last half or more of Derwatt productions were revealed as those of Bernard Tufts? Are they worse as paintings? I’m not talking about the value of good forgeries – in the news these days, and even a fad or a new industry. I’m talking about Bernard as a painter who developed from Derwatt – went on I mean.’

Back at Ed’s flat, Tom is shortly to leave for France,
‘Are any of the Derwatt drawings for sale? I gathered that in principle they’re not for sale.’
Ed Banbury smiled. ‘We are hanging on – but for you – ‘
‘How many are there? And at what price – about?’
‘Fifty or so? Prices may be from two thousand up to – fifteen, perhaps. Some Bernard Tufts’s, of course. If they’re good drawings, the price goes higher. Doesn’t always depend on size.’
‘I’d pay the normal price, of course. Be happy to.’
Ed almost laughed. ‘If you’re fond of a drawing, Tom, you deserve it as a gift! Who gets the profit after all, finally? All three of us!’
‘I may have time to look into the gallery today. Haven’t you anything here?’ Tom asked, as if Ed must have.
‘One in my bedroom, if you want to have a look.’
They went to the room at the end of the short hall. Ed lifted a framed drawing which had been leaning, face inward, against his chest of drawers. The conte and charcoal drawing showed vertical and slanting lines that might have depicted an easel, and behind it a suggestion of a figure just a bit taller than the easel. Was it a Tufts or a Derwatt? [Z1]
‘Nice.’ Tom narrowed his eyes, opened them, advanced. ‘What’s it called?’
‘”Easel in Studio”.’ Ed replied. ‘I love the warm orangey-red . Just these two lines to indicate the size of the room. Typical.’ He added, ‘I don’t hang it all the time – just six months out of the year perhaps – so it’s fresh to me.’
The drawing was nearly thirty inches high, maybe twenty broad, in an appropriately grey and neutral frame.
‘Bernard’s?’ Tom asked.
‘It’s a Derwatt. I bought it years ago – for absurdly little, I think about forty pounds. Forgot where I found it! He did it in London. Look at the hand.’ Ed extended his right hand in the same position towards the painting.
In the drawing, the right hand with an indication of a slender brush in the fingers was extended. The painter was approaching the easel, left foot delineated by a stroke of dark grey for the shoe sole.
‘Man going to work,’ said Ed. ‘It gives me courage, this picture.’

[Tom returns to the gallery to examine the drawings again]
Tom liked the first Nick pulled out, a sketch of a pigeon on a window sill, which had a few of Derwatt’s extra outlines that suggested a shifting of the alert bird. The paper, yellowish but originally off-white and of fair quality, was nevertheless deteriorating at the edges, but Tom liked that. The drawing was in charcoal and conte, under transparent plastic now.
‘And the price of this?’
‘Um – Maybe ten thousand, sir. I would have to verify that’
Tom was looking at another in the portfolio, a busy restaurant interior, which did not appeal to him, then a pair of trees and a bench in what looked like a London park. No, the pigeon. [Z2] ‘If I make a down payment – and you speak with Mr Banbury?’
Tom signed a cheque for two thousand pounds, and handed it to Nick at the desk. ‘A pity it’s not signed by Derwatt. Just not signed,’