CRI (Colour Rendering Index) scores, from 0–100, how truthfully a bulb shows colours. Most cheap LEDs score ~80, which quietly dulls reds, flattens wood and greys skin; CRI 90 is the sensible floor for living spaces and 95+ is where rooms come alive. It is independent of warmth: two 2700K bulbs can render the same room completely differently.
Here is the mystery CRI solves. Two lamps, both marked 2700K warm white, both the same brightness. Under one, the oak table is golden and the tomatoes look worth eating; under the other, everything is faintly beige and nobody can say why. The difference is on neither box in large print — it is the rendering index, and it is the most underrated number in domestic lighting.
What the number actually measures
Incandescent bulbs and daylight emit a smooth, continuous spectrum — every colour of light is present, so every colour of object can reflect truly. LEDs build their white from a blue chip and phosphors, and cheap ones leave gaps, especially in the reds. CRI measures the consequence: a set of standard colour samples is lit by the bulb and by a reference source, and the score says how closely they match. At 100, perfect fidelity. At 80 — the mass-market standard — the gaps show exactly where a home hurts most: wood tones, food, brick, skin.
| CRI | What it looks like | Where it belongs |
|---|---|---|
| ≤80 | Colours technically present, subtly dead — the "rented flat" look | Garage, loft, security fittings |
| 90 | Honest — materials read true at a glance | The whole-house floor |
| 95–97 | Rich — reds and timber glow, food looks styled, skin looks well | Kitchen, bathroom mirror, living room, anywhere you actually look at things |
Warmth and truth are different axes
Colour temperature is mood; CRI is accuracy — and they are set independently at the factory. This is why "buy warm bulbs" is only half the advice: a warm low-CRI bulb gives you cosy mud. The rooms in this series all want the same pairing — the right kelvin for the room, at CRI 90 or better. (And brightness is a third, separate axis again: lumens, covered here.)
Nimbus Pro · CRI 97
Our house bulb: 97 out of 100 for truth, in 2700K, 3000K and 4000K, dimmable. The upgrade you notice not as brighter light but as better-looking possessions.
Where the money is best spent
High-CRI bulbs cost a little more, so deploy them where colour is looked at: the kitchen (food is the most colour-critical thing in the house), the bathroom mirror (skin, twice daily), the living room (timber, fabric, art, faces). Circulation spaces and utility rooms can run standard CRI 90 stock; the garage genuinely doesn't care. A whole-house upgrade usually means a dozen bulbs — less than one mid-range fitting — and it changes how every room reads at night.
