Shader that works well with Unity3d. Tested with Collada file that had vertex colors.

VertexColor.shader

Shader "Custom/VertexColorEmissive"
{
    Properties
    {
        _MainTex("Color (RGB) Alpha (A)", 2D) = "white" {}
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic("Metallic", Range(0,1)) = 0.0
        _Emissive ("Emissive", Range(0,1)) = 1.0
        _Cutoff("Alpha cutoff", Range(0,1)) = 0.2
    }
    SubShader
    { 
        Tags {"Queue" = "AlphaTest" "RenderType" = "TransparentCutout"}

        LOD 200

        CGPROGRAM
        #pragma surface surf Standard vertex:vert alphatest:_Cutoff

        #pragma target 3.0

        sampler2D _MainTex;

        struct Input
        {
            float4 vertColor;
            float2 uv_MainTex;
        };

        half _Glossiness;
        half _Emissive;
        half _Metallic;
        fixed4 _Color;
        UNITY_INSTANCING_BUFFER_START(Props)
        UNITY_INSTANCING_BUFFER_END(Props)
        void vert(inout appdata_full v, out Input o) {
            UNITY_INITIALIZE_OUTPUT(Input, o);
            o.vertColor = v.color;
        }
        void surf (Input IN, inout SurfaceOutputStandard o)
        {
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * IN.vertColor;
            o.Albedo = c.rgb;
            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
            o.Emission = tex2D(_MainTex, IN.uv_MainTex).rgb * IN.vertColor *_Emissive;
            o.Alpha = tex2D(_MainTex, IN.uv_MainTex).a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}