The authoritative version of these rules — including the contrast floors and the entity palette — is the Color, Icons, and Contrast guide. This page is the catalog's summary of it, not a second source.
The budget
At most three semantic colours plus neutrals, each with exactly one meaning, written down:
| Colour | Means | Used for |
|---|---|---|
| Amber | a human must act, now | waiting, overdue, unsent, needs review |
| Rose / red | broken or destructive | errors, failures, delete |
| Emerald | moving the right way | positive deltas, success |
| Blue | interactive | links and buttons only — never a status |
| Slate / grey | everything informational | all other text, chips, borders |
If you cannot say in one short sentence what a colour means on this screen, make it grey.
The three rules that do the work
1. Neutral by default. Colour is preattentive — the eye spends it before reading a word — which makes it powerful and strictly limited. Most facts on most screens are informational, and informational is grey.
2. One meaning per hue, product-wide. A colour that means "draft" on one screen and "re-opened" on another has stopped being information. This is the rule that decays first, because each violation is introduced by a different person on a different page.
3. Never colour alone. Every coloured thing carries a second channel — a word, an icon, an arrow, a sign, or position. Print the page in greyscale: every value must still read. This is not only an accessibility floor, though it is that; it is also what makes the screen survive a screenshot in a document, a projector, and a phone in sunlight.
The channel rule
Marks carry identity; text and icons carry status. In a chart, colour identifies the series. In a table, colour indicates that something needs attention. Mixing the two — a status colour on a chart mark, an identity colour on a badge — is a channel collision, and the reader cannot tell which system is speaking.
Contrast is part of the meaning
A colour that fails contrast has not conveyed anything. The floors: 4.5:1 for normal text, 3:1 for large text, and 3:1 for icons, chart marks and component boundaries that carry meaning. The last one is the one most often broken — a pale grey bar on a white card fails, and a pastel status dot conveys nothing to a substantial share of readers.
The failure modes
- Rainbow status. Six hues at one saturation, some meaning two things.
- Colour-only delta. Green and red numbers with no arrow or sign.
- Naked icon. An icon with no label carrying meaning by itself.
- Channel collision. Status colour on identity marks, or the reverse.
- Pastel marks that fail the 3:1 floor and look deliberate.
- Hue in the view. Colours hard-coded into templates rather than named by role, so nobody can find or change the meaning later.
The test
Squint at the screen. A well-coloured page shows a few points of colour exactly where attention is needed, and grey everywhere else. Then take a greyscale screenshot: if anything became unreadable or ambiguous, colour was carrying that meaning alone.