The Double Diamond in UX: A Practical Guide to Design Thinking

You’ve probably heard of the double diamond. It’s a visual framework for design thinking, often used in user experience (UX) projects. But what does it actually do? And why is it still useful, even if it’s not always the most glamorous part of the design process?

The double diamond is made up of four phases: Discover, Define, Develop, and Deliver. It’s called a “double diamond” because it looks like two diamonds stacked on top of each other - the first one wide at the top, narrowing down to a point, then widening again at the bottom. That shape reflects the journey from broad exploration to focused action, then back out to a broader implementation.

Let’s break it down.

Start with Discovery: Explore, Don’t Decide

The first diamond begins with discovery. This is where you gather as much information as you can about your users, their problems, and the context in which they operate. You’re not looking for a solution yet - you’re looking for patterns. That’s why this phase is so important.

You might conduct interviews, run surveys, or observe users in their environment. You’re trying to understand their behaviours, motivations, and frustrations. The goal here is to avoid jumping to assumptions. It’s a deliberate step back from the “what if?” to the “what is?”.

Affinity mapping is often used in this phase to group insights and find themes. It’s a simple but powerful technique - you write down everything you learn, then cluster it visually. It helps you spot what’s common, what’s unique, and what might be a real opportunity.

Define: Focus on What Matters

Once you’ve collected enough data, you move into the second phase - define. This is where you narrow your focus. You’ve moved from exploring many possibilities to defining one or two key problems to solve.

This is where you start to frame your design challenge. You might create a user persona or a journey map to help visualise the problem. You’ll also begin to identify your project’s goals - what does success look like? Who will this product or service serve? What’s the biggest risk?

Cognitive load is a concept you’ll encounter here - you’re trying to make sure your design decisions are clear and not overwhelming. If your users are already stressed or confused, your solution needs to reduce that burden.

Develop: Build and Test Solutions

Now you’re ready to build. The second diamond begins to widen again - this is where you start prototyping and testing. You’re not just building for yourself - you’re building for your users.

You’ll create low-fidelity prototypes - sketches, wireframes, clickable mockups - to test your ideas. This is where you validate your assumptions. If your users can’t complete a task or don’t understand your interface, you’ll know you need to change something.

Card sorting is another technique you might use here - it helps you organise content and navigation based on how users naturally group things. It’s not about forcing your structure on them - it’s about finding the structure that works for them.

Deliver: Launch and Reflect

The final phase is deliver - the moment when your design is implemented and released. But it’s not the end. This is also where you measure, evaluate, and reflect.

You’ll collect feedback - both quantitative (e.g., usability scores) and qualitative (e.g., user interviews). You’ll look for what worked, what didn’t, and why. You might also revisit your original goals - did you meet them? If not, what changed?

This phase is where you close the loop. It’s where you learn from your users - and that’s the whole point of design thinking. You’re not just building a product - you’re building a process that continues to evolve.

Why the Double Diamond Still Works

It’s easy to dismiss the double diamond as outdated. But it’s not. It’s a framework that’s adaptable, flexible, and grounded in user research. It doesn’t prescribe a rigid process - it gives you a structure to think through your work.

It’s especially useful in projects where you’re not sure what you’re solving for. The double diamond encourages you to explore first, then decide - and then test, then refine. It’s a gentle push away from premature decisions.

It’s also a great tool for teams - it helps you align everyone around a shared understanding. You can visualise the phases, assign responsibilities, and track progress. It’s not just a diagram - it’s a conversation starter.

Practical Takeaway

If you’re working on a UX project - or even just thinking about one - try using the double diamond. Start by exploring what your users need. Then define your problem. Then build and test. Then deliver and reflect.

You don’t need to follow it strictly - but you do need to ask: “Have I explored enough?” “Am I focused on the right problem?” “Have I tested with real users?” “What did I learn?”

That’s the heart of the double diamond. It’s not about being perfect - it’s about being intentional.

And that’s why it still matters. - This post is part of UX by Example, a UK interactive glossary of user experience terms. You can explore more concepts like affinity mapping, card sorting, and cognitive load at our site.