diff --git a/cirq-core/cirq/json_resolver_cache.py b/cirq-core/cirq/json_resolver_cache.py
index c979646d7bc..da2f3777e6f 100644
--- a/cirq-core/cirq/json_resolver_cache.py
+++ b/cirq-core/cirq/json_resolver_cache.py
@@ -97,6 +97,7 @@ def _symmetricalqidpair(qids):
         'CXPowGate': cirq.CXPowGate,
         'CZPowGate': cirq.CZPowGate,
         'CZTargetGateset': cirq.CZTargetGateset,
+        'DiagonalGate': cirq.DiagonalGate,
         'DensePauliString': cirq.DensePauliString,
         'DepolarizingChannel': cirq.DepolarizingChannel,
         'DeviceMetadata': cirq.DeviceMetadata,
@@ -165,7 +166,6 @@ def _symmetricalqidpair(qids):
         'QuantumFourierTransformGate': cirq.QuantumFourierTransformGate,
         'QubitPermutationGate': cirq.QubitPermutationGate,
         'RandomGateChannel': cirq.RandomGateChannel,
-        'TensoredConfusionMatrices': cirq.TensoredConfusionMatrices,
         'RepetitionsStoppingCriteria': cirq.work.RepetitionsStoppingCriteria,
         'ResetChannel': cirq.ResetChannel,
         'Result': cirq.ResultDict,  # Keep support for Cirq < 0.14.
@@ -182,8 +182,11 @@ def _symmetricalqidpair(qids):
         'SwapPowGate': cirq.SwapPowGate,
         'SympyCondition': cirq.SympyCondition,
         'TaggedOperation': cirq.TaggedOperation,
+        'TensoredConfusionMatrices': cirq.TensoredConfusionMatrices,
         'TiltedSquareLattice': cirq.TiltedSquareLattice,
+        'ThreeQubitDiagonalGate': cirq.ThreeQubitDiagonalGate,
         'TrialResult': cirq.ResultDict,  # keep support for Cirq < 0.11.
+        'TwoQubitDiagonalGate': cirq.TwoQubitDiagonalGate,
         'TwoQubitGateTabulation': cirq.TwoQubitGateTabulation,
         '_UnconstrainedDevice': cirq.devices.unconstrained_device._UnconstrainedDevice,
         'VarianceStoppingCriteria': cirq.work.VarianceStoppingCriteria,
diff --git a/cirq-core/cirq/ops/diagonal_gate.py b/cirq-core/cirq/ops/diagonal_gate.py
index 7dc6af8adbb..c514b92f099 100644
--- a/cirq-core/cirq/ops/diagonal_gate.py
+++ b/cirq-core/cirq/ops/diagonal_gate.py
@@ -18,7 +18,18 @@
 passed as a list.
 """
 
-from typing import AbstractSet, Any, Iterator, List, Optional, Sequence, Tuple, TYPE_CHECKING, Union
+from typing import (
+    AbstractSet,
+    Any,
+    Dict,
+    Iterator,
+    List,
+    Optional,
+    Sequence,
+    Tuple,
+    TYPE_CHECKING,
+    Union,
+)
 
 import numpy as np
 import sympy
@@ -83,6 +94,10 @@ def __init__(self, diag_angles_radians: Sequence['cirq.TParamVal']) -> None:
         """
         self._diag_angles_radians: Tuple['cirq.TParamVal', ...] = tuple(diag_angles_radians)
 
+    @property
+    def diag_angles_radians(self) -> Tuple['cirq.TParamVal', ...]:
+        return self._diag_angles_radians
+
     def _num_qubits_(self):
         return int(np.log2(len(self._diag_angles_radians)))
 
@@ -194,6 +209,9 @@ def _decompose_(self, qubits: Sequence['cirq.Qid']) -> 'cirq.OP_TREE':
             decomposed_circ.extend(self._decompose_for_basis(i, bit_flip, -hat_angles[i], qubits))
         return decomposed_circ
 
+    def _json_dict_(self) -> Dict[str, Any]:
+        return protocols.obj_to_dict_helper(self, attribute_names=["diag_angles_radians"])
+
     def __repr__(self) -> str:
         return 'cirq.DiagonalGate([{}])'.format(
             ','.join(proper_repr(angle) for angle in self._diag_angles_radians)
diff --git a/cirq-core/cirq/ops/diagonal_gate_test.py b/cirq-core/cirq/ops/diagonal_gate_test.py
index 4d9d599b6a5..9bb987dab62 100644
--- a/cirq-core/cirq/ops/diagonal_gate_test.py
+++ b/cirq-core/cirq/ops/diagonal_gate_test.py
@@ -39,6 +39,10 @@ def test_consistent_protocols(gate):
     cirq.testing.assert_implements_consistent_protocols(gate)
 
 
+def test_property():
+    assert cirq.DiagonalGate([2, 3, 5, 7]).diag_angles_radians == (2, 3, 5, 7)
+
+
 @pytest.mark.parametrize('n', [1, 2, 3, 4, 5, 6, 7, 8, 9])
 def test_decomposition_unitary(n):
     diagonal_angles = np.random.randn(2**n)
diff --git a/cirq-core/cirq/ops/three_qubit_gates.py b/cirq-core/cirq/ops/three_qubit_gates.py
index 4c343c47f16..df7133acef1 100644
--- a/cirq-core/cirq/ops/three_qubit_gates.py
+++ b/cirq-core/cirq/ops/three_qubit_gates.py
@@ -18,6 +18,7 @@
     AbstractSet,
     Any,
     Collection,
+    Dict,
     List,
     Optional,
     Sequence,
@@ -221,7 +222,7 @@ class ThreeQubitDiagonalGate(raw_types.Gate):
     elements are all phases.
     """
 
-    def __init__(self, diag_angles_radians: List[value.TParamVal]) -> None:
+    def __init__(self, diag_angles_radians: Sequence[value.TParamVal]) -> None:
         r"""A three qubit gate with only diagonal elements.
 
         This gate's off-diagonal elements are zero and its on diagonal
@@ -232,7 +233,11 @@ def __init__(self, diag_angles_radians: List[value.TParamVal]) -> None:
                 If these values are $(x_0, x_1, \ldots , x_7)$ then the unitary
                 has diagonal values $(e^{i x_0}, e^{i x_1}, \ldots, e^{i x_7})$.
         """
-        self._diag_angles_radians: List[value.TParamVal] = diag_angles_radians
+        self._diag_angles_radians: Tuple[value.TParamVal, ...] = tuple(diag_angles_radians)
+
+    @property
+    def diag_angles_radians(self) -> Tuple[value.TParamVal, ...]:
+        return self._diag_angles_radians
 
     def _is_parameterized_(self) -> bool:
         return any(protocols.is_parameterized(angle) for angle in self._diag_angles_radians)
@@ -367,6 +372,9 @@ def _pauli_expansion_(self) -> value.LinearDict[str]:
             }
         )
 
+    def _json_dict_(self) -> Dict[str, Any]:
+        return protocols.obj_to_dict_helper(self, attribute_names=["diag_angles_radians"])
+
     def __repr__(self) -> str:
         return 'cirq.ThreeQubitDiagonalGate([{}])'.format(
             ','.join(proper_repr(angle) for angle in self._diag_angles_radians)
diff --git a/cirq-core/cirq/ops/three_qubit_gates_test.py b/cirq-core/cirq/ops/three_qubit_gates_test.py
index b900a7fb599..c8660cb2f26 100644
--- a/cirq-core/cirq/ops/three_qubit_gates_test.py
+++ b/cirq-core/cirq/ops/three_qubit_gates_test.py
@@ -206,6 +206,12 @@ def test_decomposition_cost(op: cirq.Operation, max_two_cost: int):
     assert two_cost == max_two_cost
 
 
+def test_diagonal_gate_property():
+    assert cirq.ThreeQubitDiagonalGate([2, 3, 5, 7, 0, 0, 0, 1]).diag_angles_radians == (
+        (2, 3, 5, 7, 0, 0, 0, 1)
+    )
+
+
 @pytest.mark.parametrize(
     'gate',
     [cirq.CCX, cirq.CSWAP, cirq.CCZ, cirq.ThreeQubitDiagonalGate([2, 3, 5, 7, 11, 13, 17, 19])],
diff --git a/cirq-core/cirq/ops/two_qubit_diagonal_gate.py b/cirq-core/cirq/ops/two_qubit_diagonal_gate.py
index 3ac00bf3ca5..2b96e5a6d2c 100644
--- a/cirq-core/cirq/ops/two_qubit_diagonal_gate.py
+++ b/cirq-core/cirq/ops/two_qubit_diagonal_gate.py
@@ -17,7 +17,7 @@
 passed as a list.
 """
 
-from typing import AbstractSet, Any, Tuple, Optional, Sequence, TYPE_CHECKING
+from typing import AbstractSet, Any, Dict, Tuple, Optional, Sequence, TYPE_CHECKING
 import numpy as np
 import sympy
 
@@ -62,6 +62,10 @@ def __init__(self, diag_angles_radians: Sequence[value.TParamVal]) -> None:
         """
         self._diag_angles_radians: Tuple[value.TParamVal, ...] = tuple(diag_angles_radians)
 
+    @property
+    def diag_angles_radians(self) -> Tuple[value.TParamVal, ...]:
+        return self._diag_angles_radians
+
     def _num_qubits_(self) -> int:
         return 2
 
@@ -134,6 +138,9 @@ def __repr__(self) -> str:
             ','.join(proper_repr(angle) for angle in self._diag_angles_radians)
         )
 
+    def _json_dict_(self) -> Dict[str, Any]:
+        return protocols.obj_to_dict_helper(self, attribute_names=["diag_angles_radians"])
+
     def _quil_(
         self, qubits: Tuple['cirq.Qid', ...], formatter: 'cirq.QuilFormatter'
     ) -> Optional[str]:
diff --git a/cirq-core/cirq/ops/two_qubit_diagonal_gate_test.py b/cirq-core/cirq/ops/two_qubit_diagonal_gate_test.py
index f72550174de..405b0fcd029 100644
--- a/cirq-core/cirq/ops/two_qubit_diagonal_gate_test.py
+++ b/cirq-core/cirq/ops/two_qubit_diagonal_gate_test.py
@@ -34,6 +34,10 @@ def test_consistent_protocols(gate):
     cirq.testing.assert_implements_consistent_protocols(gate)
 
 
+def test_property():
+    assert cirq.TwoQubitDiagonalGate([2, 3, 5, 7]).diag_angles_radians == (2, 3, 5, 7)
+
+
 def test_parameterized_decompose():
     angles = sympy.symbols('x0, x1, x2, x3')
     parameterized_op = cirq.TwoQubitDiagonalGate(angles).on(*cirq.LineQubit.range(2))
diff --git a/cirq-core/cirq/protocols/json_test_data/DiagonalGate.json b/cirq-core/cirq/protocols/json_test_data/DiagonalGate.json
new file mode 100644
index 00000000000..96ab1e498c4
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/DiagonalGate.json
@@ -0,0 +1,9 @@
+{
+  "cirq_type": "DiagonalGate",
+  "diag_angles_radians": [
+    0.0,
+    1.0,
+    -1.0,
+    0.0
+  ]
+}
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/DiagonalGate.repr b/cirq-core/cirq/protocols/json_test_data/DiagonalGate.repr
new file mode 100644
index 00000000000..1cedb5597ca
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/DiagonalGate.repr
@@ -0,0 +1 @@
+cirq.DiagonalGate(diag_angles_radians=[0.0, 1.0, -1.0, 0.0])
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.json b/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.json
new file mode 100644
index 00000000000..24f07e9af08
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.json
@@ -0,0 +1,13 @@
+{
+  "cirq_type": "ThreeQubitDiagonalGate",
+  "diag_angles_radians": [
+    0.0,
+    1.0,
+    -1.0,
+    0.0,
+    0.5,
+    0.5,
+    0.5,
+    0.5
+  ]
+}
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.repr b/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.repr
new file mode 100644
index 00000000000..8af9dec393d
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/ThreeQubitDiagonalGate.repr
@@ -0,0 +1 @@
+cirq.ThreeQubitDiagonalGate(diag_angles_radians=[0.0, 1.0, -1.0, 0.0, 0.5, 0.5, 0.5, 0.5])
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.json b/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.json
new file mode 100644
index 00000000000..5130515f1c4
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.json
@@ -0,0 +1,9 @@
+{
+  "cirq_type": "TwoQubitDiagonalGate",
+  "diag_angles_radians": [
+    0.0,
+    1.0,
+    -1.0,
+    0.0
+  ]
+}
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.repr b/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.repr
new file mode 100644
index 00000000000..1cf76594eb5
--- /dev/null
+++ b/cirq-core/cirq/protocols/json_test_data/TwoQubitDiagonalGate.repr
@@ -0,0 +1 @@
+cirq.TwoQubitDiagonalGate(diag_angles_radians=[0.0, 1.0, -1.0, 0.0])
\ No newline at end of file
diff --git a/cirq-core/cirq/protocols/json_test_data/spec.py b/cirq-core/cirq/protocols/json_test_data/spec.py
index dd183f37e68..1b8adc82779 100644
--- a/cirq-core/cirq/protocols/json_test_data/spec.py
+++ b/cirq-core/cirq/protocols/json_test_data/spec.py
@@ -44,7 +44,6 @@
         'LinearCombinationOfOperations',
         'Linspace',
         'ListSweep',
-        'DiagonalGate',
         'NeutralAtomDevice',
         'PauliInteractionGate',
         'PauliSumCollector',
@@ -65,9 +64,7 @@
         'SparseSimulatorStep',
         'StateVectorMixin',
         'TextDiagramDrawer',
-        'ThreeQubitDiagonalGate',
         'Timestamp',
-        'TwoQubitDiagonalGate',
         'TwoQubitGateTabulationResult',
         'UnitSweep',
         'StateVectorSimulatorState',