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Colour guides · Blue
'Deep blue' covers at least three families: night blues that lean violet, ink blues that lean grey, and petrol blues that lean green. On a colour card they look alike; across four walls they make very different rooms.
Here are our eight deep blues, compared on what really matters: undertone, the light they return, and the room where each excels.
Updated September 2026 · by the Mylands France colour team
The short answer
The most versatile of our deep blues is Proper Blue No.67, an ink blue with a grey-green undertone that goes from kitchen cabinets to living-room walls. For a more violet, more enveloping blue, Observatory No.34 or Blueprint No.50; for a blue-grey that is almost a neutral, Bond Street No.219 or Mayfair Dark No.218.
At a glance
| Colour | Family | Tone | Light | LRV ≈ | Best for |
|---|---|---|---|---|---|
| Proper Blue™ No.67 | Blue | Dark tone | South | 7 % | Kitchen cabinets, doors, dining-room walls |
| Observatory™ No.34 | Blue | Dark tone | South | 11 % | Living room, bedroom, north-facing rooms |
| Blueprint™ No.50 | Neutral | Dark tone | North | 6 % | Library, study, dining room — colour-drenched |
| Mayfair Dark™ No.218 | Neutral | Dark tone | North | 13 % | Furniture, woodwork, a back wall behind pictures |
| Bond Street™ No.219 | Neutral | Dark tone | North | 8 % | Front doors, shutters, kitchens, staircases |
| Murmuration JB.11 | Neutral | Dark tone | North | 7 % | Garden rooms, conservatories, outdoor furniture |
| Thunder BH.12 | Neutral | Dark tone | North | 11 % | Painted furniture, woodwork, kitchen |
| Maritime™ No.236 | Neutral | Dark tone | North | 15 % | Bedroom, bathroom, study |
LRV: light reflectance estimated from the on-screen shade, from 0 (absolute black) to 100 (absolute white). Light: the orientation in which the shade looks its best.
8 colours
The ink blue
A deep, candid blue, tempered by a grey-green undertone that stops it turning into office navy. It is our most-used blue, and for good reason: it holds on kitchen cabinets as on dining-room walls, likes brass as much as oak, and stays blue — not black — once evening comes. From the archive, it has the patina of an old blue.
Our tip — Kitchen cabinets, doors, dining-room walls
The night blue
A deep blue-grey sliding towards violet — the colour of the sky an hour after sunset. Softer and lighter than Proper Blue, it is also warmer thanks to that hint of violet, which makes it the easiest deep blue in a north-facing room. Under lamps it turns to velvet.
Our tip — Living room, bedroom, north-facing rooms
The darkest
Our deepest blue: a slate blue that is almost black, with a violet undertone, returning only 6% of the light. It is a colour-drenching blue — walls, ceiling, woodwork — for a library, a study or an evening dining room. By day it is grave; at night, with candles and brass, it is sumptuous.
Our tip — Library, study, dining room — colour-drenched
The blue-grey
A blue so greyed it behaves like a deep neutral: from a distance you hesitate between blue and grey; up close, the blue wins. It is the most discreet deep blue on the list, the one that accepts any colour beside it — rust, ochre, pink, green — without argument. An excellent furniture blue.
Our tip — Furniture, woodwork, a back wall behind pictures
The slate
Darker and greyer than Mayfair Dark: the blue of wet slate, with a faintly green undertone that makes it mineral. It has Blueprint's depth without its gravity, and works very well outdoors — doors, shutters, gates — as much as in. Superb with raw timber and stone.
Our tip — Front doors, shutters, kitchens, staircases
The storm blue
Drawn by Jinny Blom from the starling murmurations of an autumn sky: a deep, cool blue, closer to Bond Street than to Observatory, with a hint of grey holding it. It is a landscape blue more than a drawing-room blue — it makes most sense facing a garden, in a room that opens to the outside.
Our tip — Garden rooms, conservatories, outdoor furniture
The thunder blue
A dark blue-grey from the Beata Heuman collection, the colour of a storm sky over the sea. It is lighter than Blueprint and greyer than Proper Blue, with a verdigris undertone. Beata recommends it for painted furniture and woodwork, where it makes a perfect ground for the more cheerful colours of her collection.
Our tip — Painted furniture, woodwork, kitchen
The least deep
The lightest of the eight: a mid-deep blue-grey with a green undertone, the colour of northern seas. It returns twice the light of Blueprint, which makes it the 'deep blue' that is possible in a bedroom or bathroom you don't want to darken. It ages beautifully with off-whites and blond timber.
Our tip — Bedroom, bathroom, study
The undertone decides the room. Violet-undertoned blues — Observatory No.34, Blueprint No.50 — are the warmest and most enveloping: living-room and bedroom blues. Green- or grey-undertoned blues — Proper Blue No.67, Bond Street No.219, Maritime No.236 — are cooler and more mineral: kitchen, bathroom and exterior blues.
Light reflectance (LRV) says how much the room will darken. Between 6% (Blueprint No.50) and 15% (Maritime No.236), the difference is that between an evening library and a morning bedroom. None of these blues suits a room you want bright; all of them suit a room you want beautiful.
Midnight FTT-017 and Ultramarine Blue FTT-018, from the film-and-theatre palette, are deep but saturated blues — a vivid petrol and an electric ultramarine — that don't compare with the ink blues above. They are accent colours, superb on a door or a piece of furniture, hard work on four walls.
A deep blue asks for a white that isn't blue: Limestone No.55, Cavendish Cream No.120 or Holland Park No.5 rather than Pure White No.1, which chills them. And a warm colour somewhere — an ochre such as Golden Square No.131, a pink such as Soho Pink No.266, a terracotta such as Coral Orange No.277 — so the room doesn't tip into night. See also our blues for a bedroom, our blue schemes and all our blues.
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