diff --git a/search/search_quality/assessment_tool/context.cpp b/search/search_quality/assessment_tool/context.cpp
index 228ae37477..ec69243651 100644
--- a/search/search_quality/assessment_tool/context.cpp
+++ b/search/search_quality/assessment_tool/context.cpp
@@ -53,22 +53,22 @@ search::Sample Context::MakeSample(search::FeatureLoader & loader) const
     {
       auto const & entry = nonFoundEntries[k++];
       auto const deleted = entry.m_deleted;
-      auto const relevance = entry.m_curr;
-      if (!deleted && relevance != search::Sample::Result::Relevance::Irrelevant)
+      auto const & curr = entry.m_curr;
+      if (!deleted && !curr.m_unknown)
       {
         auto result = m_sample.m_results[i];
-        result.m_relevance = relevance;
+        result.m_relevance = curr.m_relevance;
         outResults.push_back(result);
       }
       continue;
     }
 
     // No need to keep irrelevant results.
-    if (foundEntries[j].m_curr == search::Sample::Result::Relevance::Irrelevant)
+    if (foundEntries[j].m_curr.m_unknown)
       continue;
 
     auto result = m_sample.m_results[i];
-    result.m_relevance = foundEntries[j].m_curr;
+    result.m_relevance = foundEntries[j].m_curr.m_relevance;
     outResults.push_back(move(result));
   }
 
@@ -83,7 +83,7 @@ search::Sample Context::MakeSample(search::FeatureLoader & loader) const
     }
 
     // No need to keep irrelevant results.
-    if (foundEntries[i].m_curr == search::Sample::Result::Relevance::Irrelevant)
+    if (foundEntries[i].m_curr.m_unknown)
       continue;
 
     auto const & result = m_foundResults[i];
@@ -93,7 +93,7 @@ search::Sample Context::MakeSample(search::FeatureLoader & loader) const
 
     FeatureType ft;
     CHECK(loader.Load(result.GetFeatureID(), ft), ());
-    outResults.push_back(search::Sample::Result::Build(ft, foundEntries[i].m_curr));
+    outResults.push_back(search::Sample::Result::Build(ft, foundEntries[i].m_curr.m_relevance));
   }
 
   return outSample;
diff --git a/search/search_quality/assessment_tool/edits.cpp b/search/search_quality/assessment_tool/edits.cpp
index 62ffed2ef3..9cd760176c 100644
--- a/search/search_quality/assessment_tool/edits.cpp
+++ b/search/search_quality/assessment_tool/edits.cpp
@@ -13,7 +13,7 @@ bool Edits::Editor::Set(Relevance relevance)
   return m_parent.SetRelevance(m_index, relevance);
 }
 
-Edits::Relevance Edits::Editor::Get() const
+Edits::MaybeRelevance Edits::Editor::Get() const
 {
   return m_parent.Get(m_index).m_curr;
 }
@@ -38,7 +38,7 @@ void Edits::Apply()
   });
 }
 
-void Edits::Reset(std::vector<Relevance> const & relevances)
+void Edits::Reset(std::vector<MaybeRelevance> const & relevances)
 {
   WithObserver(Update::MakeAll(), [this, &relevances]() {
     m_entries.resize(relevances.size());
@@ -61,12 +61,14 @@ bool Edits::SetRelevance(size_t index, Relevance relevance)
 
     auto & entry = m_entries[index];
 
-    if (entry.m_curr != entry.m_orig && relevance == entry.m_orig)
+    MaybeRelevance const r(relevance);
+
+    if (entry.m_curr != entry.m_orig && r == entry.m_orig)
       --m_numEdits;
-    else if (entry.m_curr == entry.m_orig && relevance != entry.m_orig)
+    else if (entry.m_curr == entry.m_orig && r != entry.m_orig)
       ++m_numEdits;
 
-    entry.m_curr = relevance;
+    entry.m_curr = r;
     return entry.m_curr != entry.m_orig;
   });
 }
@@ -125,9 +127,9 @@ Edits::Entry const & Edits::GetEntry(size_t index) const
   return m_entries[index];
 }
 
-std::vector<Edits::Relevance> Edits::GetRelevances() const
+std::vector<Edits::MaybeRelevance> Edits::GetRelevances() const
 {
-  std::vector<Relevance> relevances(m_entries.size());
+  std::vector<MaybeRelevance> relevances(m_entries.size());
   for (size_t i = 0; i < m_entries.size(); ++i)
     relevances[i] = m_entries[i].m_curr;
   return relevances;
diff --git a/search/search_quality/assessment_tool/edits.hpp b/search/search_quality/assessment_tool/edits.hpp
index 1d032f95a9..68e2763d8c 100644
--- a/search/search_quality/assessment_tool/edits.hpp
+++ b/search/search_quality/assessment_tool/edits.hpp
@@ -15,6 +15,31 @@ class Edits
 public:
   using Relevance = search::Sample::Result::Relevance;
 
+  struct MaybeRelevance
+  {
+    MaybeRelevance() = default;
+    MaybeRelevance(search::Sample::Result::Relevance relevance)
+      : m_relevance(relevance), m_unknown(false)
+    {
+    }
+
+    bool operator==(MaybeRelevance const & rhs) const
+    {
+      if (m_unknown && rhs.m_unknown)
+        return true;
+      if (m_unknown != rhs.m_unknown)
+        return false;
+      ASSERT(!m_unknown, ());
+      ASSERT(!rhs.m_unknown, ());
+      return m_relevance == rhs.m_relevance;
+    }
+
+    bool operator!=(MaybeRelevance const & rhs) const { return !(*this == rhs); }
+
+    Relevance m_relevance = Relevance::Irrelevant;
+    bool m_unknown = true;
+  };
+
   struct Entry
   {
     enum class Type
@@ -24,13 +49,12 @@ public:
     };
 
     Entry() = default;
-    Entry(Relevance relevance, Type type)
-      : m_curr(relevance), m_orig(relevance), m_type(type)
+    Entry(MaybeRelevance relevance, Type type) : m_curr(relevance), m_orig(relevance), m_type(type)
     {
     }
 
-    Relevance m_curr = Relevance::Irrelevant;
-    Relevance m_orig = Relevance::Irrelevant;
+    MaybeRelevance m_curr = {};
+    MaybeRelevance m_orig = {};
     bool m_deleted = false;
     Type m_type = Type::Loaded;
   };
@@ -71,7 +95,7 @@ public:
     // Sets relevance to |relevance|. Returns true iff |relevance|
     // differs from the original one.
     bool Set(Relevance relevance);
-    Relevance Get() const;
+    MaybeRelevance Get() const;
     bool HasChanges() const;
     Entry::Type GetType() const;
 
@@ -83,7 +107,7 @@ public:
   explicit Edits(OnUpdate onUpdate) : m_onUpdate(onUpdate) {}
 
   void Apply();
-  void Reset(std::vector<Relevance> const & relevances);
+  void Reset(std::vector<MaybeRelevance> const & relevances);
 
   // Sets relevance at |index| to |relevance|. Returns true iff
   // |relevance| differs from the original one.
@@ -102,7 +126,7 @@ public:
   Entry & GetEntry(size_t index);
   Entry const & GetEntry(size_t index) const;
   size_t NumEntries() const { return m_entries.size(); }
-  std::vector<Relevance> GetRelevances() const;
+  std::vector<MaybeRelevance> GetRelevances() const;
 
   Entry const & Get(size_t index) const;
 
diff --git a/search/search_quality/assessment_tool/main_model.cpp b/search/search_quality/assessment_tool/main_model.cpp
index 10cc8b3995..9057b716d2 100644
--- a/search/search_quality/assessment_tool/main_model.cpp
+++ b/search/search_quality/assessment_tool/main_model.cpp
@@ -141,7 +141,7 @@ void MainModel::OnSampleSelected(int index)
     search::SearchParams params;
     sample.FillSearchParams(params);
     params.m_onResults = [this, index, sample, timestamp](search::Results const & results) {
-      vector<Relevance> relevances;
+      vector<Edits::MaybeRelevance> relevances;
       vector<size_t> goldenMatching;
       vector<size_t> actualMatching;
 
@@ -153,14 +153,14 @@ void MainModel::OnSampleSelected(int index)
 
         vector<search::Result> const actual(results.begin(), results.end());
         matcher.Match(sample.m_results, actual, goldenMatching, actualMatching);
-        relevances.assign(actual.size(), Relevance::Irrelevant);
+        relevances.resize(actual.size());
         for (size_t i = 0; i < goldenMatching.size(); ++i)
         {
           auto const j = goldenMatching[i];
           if (j != search::Matcher::kInvalidId)
           {
             CHECK_LESS(j, relevances.size(), ());
-            relevances[j] = sample.m_results[i].m_relevance;
+            relevances[j] = Edits::MaybeRelevance(sample.m_results[i].m_relevance);
           }
         }
       }
@@ -312,7 +312,7 @@ void MainModel::OnUpdate(View::ResultType type, size_t sampleIndex, Edits::Updat
 }
 
 void MainModel::OnResults(uint64_t timestamp, size_t sampleIndex, search::Results const & results,
-                          vector<Relevance> const & relevances,
+                          vector<Edits::MaybeRelevance> const & relevances,
                           vector<size_t> const & goldenMatching,
                           vector<size_t> const & actualMatching)
 {
@@ -338,7 +338,7 @@ void MainModel::OnResults(uint64_t timestamp, size_t sampleIndex, search::Result
     context.m_actualMatching = actualMatching;
 
     {
-      vector<Relevance> relevances;
+      vector<Edits::MaybeRelevance> relevances;
 
       auto & nonFound = context.m_nonFoundResults;
       CHECK(nonFound.empty(), ());
@@ -348,7 +348,7 @@ void MainModel::OnResults(uint64_t timestamp, size_t sampleIndex, search::Result
         if (j != search::Matcher::kInvalidId)
           continue;
         nonFound.push_back(context.m_sample.m_results[i]);
-        relevances.push_back(nonFound.back().m_relevance);
+        relevances.emplace_back(nonFound.back().m_relevance);
       }
       context.m_nonFoundResultsEdits.Reset(relevances);
     }
diff --git a/search/search_quality/assessment_tool/main_model.hpp b/search/search_quality/assessment_tool/main_model.hpp
index 6276e87381..5575429295 100644
--- a/search/search_quality/assessment_tool/main_model.hpp
+++ b/search/search_quality/assessment_tool/main_model.hpp
@@ -47,7 +47,7 @@ private:
   void OnUpdate(View::ResultType type, size_t sampleIndex, Edits::Update const & update);
 
   void OnResults(uint64_t timestamp, size_t sampleIndex, search::Results const & results,
-                 std::vector<search::Sample::Result::Relevance> const & relevances,
+                 std::vector<Edits::MaybeRelevance> const & relevances,
                  std::vector<size_t> const & goldenMatching,
                  std::vector<size_t> const & actualMatching);
 
diff --git a/search/search_quality/assessment_tool/result_view.cpp b/search/search_quality/assessment_tool/result_view.cpp
index 83d9bf989a..8e8c8607ce 100644
--- a/search/search_quality/assessment_tool/result_view.cpp
+++ b/search/search_quality/assessment_tool/result_view.cpp
@@ -71,11 +71,15 @@ void ResultView::SetEditor(Edits::Editor && editor)
   m_relevant->setChecked(false);
   m_vital->setChecked(false);
 
-  switch (m_editor->Get())
+  auto const & r = m_editor->Get();
+  if (!r.m_unknown)
   {
-  case Relevance::Irrelevant: m_irrelevant->setChecked(true); break;
-  case Relevance::Relevant: m_relevant->setChecked(true); break;
-  case Relevance::Vital: m_vital->setChecked(true); break;
+    switch (r.m_relevance)
+    {
+      case Relevance::Irrelevant: m_irrelevant->setChecked(true); break;
+      case Relevance::Relevant: m_relevant->setChecked(true); break;
+      case Relevance::Vital: m_vital->setChecked(true); break;
+    }
   }
 
   setEnabled(true);