diff --git a/bec_widgets/utils/colors.py b/bec_widgets/utils/colors.py
index 488c8886..31c4eb4f 100644
--- a/bec_widgets/utils/colors.py
+++ b/bec_widgets/utils/colors.py
@@ -250,7 +250,7 @@ class Colors:
                 if not 0 <= value <= 255:
                     raise PydanticCustomError(
                         "unsupported color",
-                        f"The color values must be between 0 and 255. Provide color {color}.",
+                        f"The color values must be between 0 and 255 in RGBA format (R,G,B,A)",
                         {"wrong_value": color},
                     )
             return color
diff --git a/tests/unit_tests/test_color_validation.py b/tests/unit_tests/test_color_validation.py
new file mode 100644
index 00000000..4766b8ac
--- /dev/null
+++ b/tests/unit_tests/test_color_validation.py
@@ -0,0 +1,60 @@
+import pytest
+from pydantic import ValidationError
+
+from bec_widgets.utils import Colors
+from bec_widgets.widgets.figure.plots.waveform.waveform_curve import CurveConfig
+
+
+def test_color_validation_CSS():
+    # Test valid color
+    color = Colors.validate_color("teal")
+    assert color == "teal"
+
+    # Test invalid color
+    with pytest.raises(ValidationError) as excinfo:
+        CurveConfig(color="invalid_color")
+
+    errors = excinfo.value.errors()
+    assert len(errors) == 1
+    assert errors[0]["type"] == ("unsupported color")
+    assert "The color must be a valid HEX string or CSS Color." in str(excinfo.value)
+
+
+def test_color_validation_hex():
+    # Test valid color
+    color = Colors.validate_color("#ff0000")
+    assert color == "#ff0000"
+
+    # Test invalid color
+    with pytest.raises(ValidationError) as excinfo:
+        CurveConfig(color="#ff00000")
+
+    errors = excinfo.value.errors()
+    assert len(errors) == 1
+    assert errors[0]["type"] == ("unsupported color")
+    assert "The color must be a valid HEX string or CSS Color." in str(excinfo.value)
+
+
+def test_color_validation_RGBA():
+    # Test valid color
+    color = Colors.validate_color((255, 0, 0, 255))
+    assert color == (255, 0, 0, 255)
+
+    # Test invalid color
+    with pytest.raises(ValidationError) as excinfo:
+        CurveConfig(color=(255, 0, 0))
+
+    errors = excinfo.value.errors()
+    assert len(errors) == 1
+    assert errors[0]["type"] == ("unsupported color")
+    assert "The color must be a tuple of 4 elements (R, G, B, A)." in str(excinfo.value)
+
+    with pytest.raises(ValidationError) as excinfo:
+        CurveConfig(color=(255, 0, 0, 355))
+
+    errors = excinfo.value.errors()
+    assert len(errors) == 1
+    assert errors[0]["type"] == ("unsupported color")
+    assert "The color values must be between 0 and 255 in RGBA format (R,G,B,A)" in str(
+        excinfo.value
+    )