The double diamond: diverging and converging in design

The Design Council double diamond has four phases (discover, define, develop, deliver) and alternates diverging and converging. How to use it and its limits.

info Quick Definition

The double diamond is a design process model with four phases: discover, define, develop and deliver. Two diamonds represent alternating between diverging, exploring the problem or the solutions broadly, and converging, focusing on a concrete definition or solution.

Where does it come from and what does it propose?

Dates vary by source. According to the history published by the Design Council itself, the model began in 2003, when its design and innovation team, led by Richard Eisermann, asked how to describe the design process, and in 2004 it started presenting it at conferences. English Wikipedia says it was popularized in 2005. That team built on earlier research proposing models with elements of divergence and convergence; Wikipedia mentions the model Béla H. Bánáthy proposed in 1996, although the Design Council does not present him as the creator of the double diamond.

The Design Council framed it as a visual way of explaining how design work happens: first the problem opens up, then it closes into a definition, then the solutions open up, and finally they close into a delivery.

The four phases, according to the Design Council itself:

Discover: explore the problem broadly, through research and conversations with the people affected.
Define: use what was learned to reframe the challenge and narrow the problem, until there is a definition that guides the work.
Develop: generate different responses to the defined problem, with outside inspiration, and co-design them with diverse people.
Deliver: test different solutions at small scale, drop the ones that will not work and refine the ones that will.

Why does it matter to a designer?

Because it sorts out two common errors. The first is jumping to a solution before understanding the problem. The second is exploring forever without ever deciding. The double diamond asks you to do both in order: open to understand, close to decide, open to propose, close to deliver.

It is also a shared language. A product manager, an engineer and a designer can say “we are in the first diamond” and everyone knows it is not yet time to choose a solution. That clarity matters when the team is under pressure for results.

How do you apply it in practice?

Each diamond has its own way of working:

First diamond, diverge. Interviews, observation, data analysis, review of what already exists. The goal is to gather enough material not to decide blindly. This is where generative research belongs, the kind that seeks to understand before evaluating.
First diamond, converge. Group findings, detect patterns and write the problem definition as a question. If you cannot write it in one sentence, you have not converged yet.
Second diamond, diverge. Generate many ideas, sketches and variants. Techniques such as crazy 8s or strategic workshops help you open up without losing focus.
Second diamond, converge. Choose, prototype and test with users. This is where the solution that reaches production is closed, against explicit criteria.

A useful question for each phase: am I opening to understand or closing to decide? If the team does not know, it is probably mixing both in the same meeting.

The double diamond also works as a map for other methods. If your team works with design thinking or design sprints, it lets you place each activity in one of the two phases, opening or closing. That shows at a glance whether today’s meeting needs to open, close or both, and keeps an ideas session from turning into a decision session with no data.

When should you NOT use it?

When the decision is already made and the work is execution. A full double diamond to change a colour is disproportionate.
When the team uses the model as a rigid sequence. The Design Council says the process is not linear; treated as a chain of deliverables, it loses its meaning.
When there is no access to users. A discovery phase without real people becomes a list of assumptions with a nice format.
When the problem is technical and bounded, such as a migration. A more specific process, such as a design sprint, may be more efficient.

There is also a warning worth keeping in mind. NN/g, describing design thinking, advises against seeing it as a prescribed step-by-step recipe for success. The double diamond runs the same risk: it invites being read as a sequence, and used as a checklist it adds the least value.

What did the Framework for Innovation add?

The Design Council published the Framework for Innovation in 2019, according to its 2019/20 annual report, and keeps the double diamond at its centre. According to the framework page, it adds three things to the diagram:

Four design principles: put people first, communicate visually and inclusively, collaborate and co-create, and iterate, iterate, iterate.
A methods bank, organized into Explore (challenges, needs and opportunities), Shape (prototypes, insights and visions) and Build (ideas, plans and expertise).
Two culture elements: leadership, which encourages innovation and experimentation, and engagement of the people who deliver and receive the ideas, plus partners.

The same page repeats that the process is not linear, as the arrows in the diagram show. In 2023 the Design Council released the double diamond under a Creative Commons licence, so you can reuse and adapt the diagram with attribution.

Example

Illustrative example: a transport cooperative wants to improve trip booking for older people. In the first diamond, interviews reveal that most do not book through the app but by phone, and that the barrier is the language of the forms. They define the problem as: “How can an older person book a trip without using the phone or understanding technical terms?” In the second diamond they generate twelve ideas in an afternoon, prototype two flows on paper and test them with five people. The flow that asks one question at a time, with spoken confirmation, wins. The team ships a pilot on a single route and measures how many bookings complete without a phone call.

For your next project: write in one line which diamond you are in. If the answer changes every week, the team is jumping between phases without closing any of them.

Common mistakes

Skipping the first diamond and designing the solution on assumptions.
Staying in the first diamond and never deciding.
Converging too early, with only one idea on the table.
Treating phases as independent deliverables instead of a cycle that iterates.
Running the second diamond without prototypes, only in discussion.
Forgetting the delivery phase: without testing at small scale, the diamond stays an opinion.

Sources

Frequently asked questions

What is the double diamond in design?

It is a design process model with four phases: discover, define, develop and deliver. The two diamonds represent alternating between exploring the problem broadly (diverging) and focusing action (converging).

Who created the double diamond?

A team at the British Design Council created it. By the Council’s own history it developed the model in 2003 and began presenting it at conferences in 2004; other sources, such as Wikipedia, say it was popularized in 2005. It built on earlier research into divergence and convergence, and Wikipedia lists among it the model Béla H. Bánáthy proposed in 1996.

What is the difference between diverging and converging?

Diverging means exploring many options or understanding a problem in depth; converging means choosing, defining and acting on a specific option. The double diamond alternates both movements twice: first on the problem, then on the solution.

Is the double diamond a linear process?

No. The Design Council says it is not linear and that the arrows in the diagram show continuous iteration. Even so, many teams use it as a rigid sequence, and that is where it loses its usefulness.