Learn the Double Diamond design framework, its four phases (Discover, Define, Develop, Deliver), how it compares to design thinking, and how to apply it in real projects.
The Double Diamond is a visual model for the design process, developed by the British Design Council in 2005. It describes how designers move through two cycles of divergent and convergent thinking: first to understand the problem, then to create the solution. The model has become one of the most widely taught frameworks in design education, and its simplicity is both its greatest strength and its most common source of misunderstanding.
The framework gets its name from the shape it creates when you draw it. Two diamonds sit side by side. The first diamond represents the problem space. The second represents the solution space. Each diamond has a divergent phase (going wide) followed by a convergent phase (narrowing down).
The left edge of the first diamond is where you start: with a design brief, a challenge, or an observed problem. You then expand outward (diverge) to explore and understand the problem from multiple angles. At the widest point, you have gathered a large amount of research, observations, and data. Then you converge, synthesizing what you have learned into a clear problem definition. The meeting point between the two diamonds represents the moment when you have a well-framed problem statement.
The second diamond begins with that defined problem. You diverge again, this time generating ideas and exploring possible solutions. At the widest point, you have many potential approaches. Then you converge once more, testing, refining, and selecting until you arrive at a solution that works.
The Discover phase is about looking beyond your initial assumptions. Instead of jumping to solutions, you spend time with the people who experience the problem. You observe their behavior, interview them, and gather data about the context in which the problem exists.
The tools commonly used in this phase include user interviews, contextual observation, desk research, and stakeholder mapping. The purpose is not to confirm what you already think. It is to discover things you did not expect. The best insights in the Discover phase come from moments where the research contradicts your assumptions.
A practical example: a hospital wanted to reduce emergency department wait times. In the Discover phase, the design team observed that patients were not actually frustrated by the wait itself. They were frustrated by the uncertainty: not knowing how long the wait would be, not knowing what was happening, and not knowing whether they had been forgotten. The real problem was information, not speed. This insight only emerged because the team spent time observing and interviewing rather than jumping to queue-management solutions.
The Define phase takes everything you gathered during Discover and distills it into a clear, actionable problem statement. This is a convergent phase. You are narrowing down, looking for patterns, and making decisions about which problem is most worth solving.
The tools for this phase include affinity diagrams, empathy maps, How Might We questions, and point-of-view statements. The output should be specific enough to guide solution generation but open enough to allow creative exploration. "Patients feel anxious during emergency department waits because they lack information about their status and timeline" is a well-defined problem. "Fix the ER" is not.
Teams commonly rush this phase because defining feels less productive than building. This is a mistake. A poorly defined problem leads to solutions that address symptoms rather than causes. The time you invest in Define directly determines the quality of everything that follows.
With a clear problem definition, you enter the second diamond. The Develop phase is about generating possible solutions. Like the Discover phase, this is divergent: you want to explore as many approaches as possible before committing to one.
Brainstorming, Crazy 8s sketching, design workshops, and concept sketching are all common activities in this phase. The key discipline is to separate idea generation from idea evaluation. Generate first, judge later. Teams that evaluate ideas as they generate them produce fewer and less creative solutions.
For the hospital example, the Develop phase produced ideas ranging from digital status boards and SMS updates to volunteer greeters and redesigned waiting areas. The team explored solutions across technology, physical space, and human interaction rather than anchoring on the first idea that seemed viable.
The Deliver phase converges on a final solution through testing, iteration, and refinement. You build prototypes, test them with real users, gather feedback, and improve. The solution becomes progressively more refined until it is ready for implementation.
This phase includes user testing, pilot programs, refinement cycles, and final implementation. The Deliver phase is not a single event. It is an iterative process where each round of testing reveals improvements that make the solution more effective.
The Double Diamond's most important contribution is making explicit the rhythm of divergent and convergent thinking. Divergent thinking is about generating options, exploring possibilities, and suspending judgment. Convergent thinking is about making decisions, prioritizing, and narrowing focus.
Most teams default to convergent thinking. They want to make decisions quickly, reach conclusions, and move forward. The Double Diamond pushes back on this instinct by insisting on deliberate divergent phases. The quality of your convergent decisions depends directly on the breadth of your divergent exploration.
In practice, this means resisting the urge to solve during the Discover phase, and resisting the urge to commit during the Develop phase. Let each phase do its job fully before transitioning to the next.
The Double Diamond and design thinking are closely related but not identical. Design thinking, as popularized by Stanford's d.school, describes five stages: Empathize, Define, Ideate, Prototype, and Test. The six-stage model adds an Initialize stage before Empathize.
The conceptual mapping is straightforward:
The difference is primarily in emphasis and framing. The Double Diamond emphasizes the diverge-converge rhythm and is deliberately methodology-agnostic; it does not prescribe specific tools or activities. Design thinking provides more prescriptive guidance about what to do in each stage. Many teams use both: the Double Diamond as a mental model for where they are in the process, and design thinking methods as the specific activities they perform.
In 2019, the Design Council updated the framework to include the "design principles" that surround and support the two diamonds. These principles acknowledge that the process does not happen in a vacuum:
The updated model also added a "leadership" and "engagement" layer, recognizing that design processes need organizational support and stakeholder buy-in to succeed. This reflects a maturation in the design community's understanding: good process is necessary but not sufficient. You also need the organizational conditions that allow the process to produce results.
The Double Diamond is most valuable when:
It is less useful when the problem is already well-defined and you need to move quickly, or when you need detailed, step-by-step guidance about which activities to perform. In those cases, a more prescriptive framework like design thinking's stage model or a design sprint may be more practical.
You do not need to run a formal Double Diamond process to benefit from the model. The most practical application is simply asking yourself two questions at any point in a project: "Am I in the problem space or the solution space?" and "Should I be diverging or converging right now?"
If you find yourself building solutions without having explored the problem, you are in the wrong diamond. If you find yourself committed to a single idea without having explored alternatives, you are converging too early. The Double Diamond's greatest value is as a diagnostic tool that helps you recognize where you are and whether you are doing the right kind of thinking for that moment.
The Double Diamond gives teams a shared vocabulary for knowing whether they should be expanding possibilities or narrowing toward decisions. If you are new to design thinking itself, the guide on what design thinking is provides the foundational context. For a detailed comparison of how the five-stage and six-stage models map onto the diamond structure, see the stages breakdown. Teams ready to compress this process into a single week will find the Design Sprint comparison especially useful, and facilitation techniques will help you guide a group through each phase transition without losing momentum.
Related guides: divergent vs convergent thinking · what is design thinking · design thinking stages
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