using System;

public class Program

{

    public static void Main()

    {

        var o = new TestClass{ TestValue = TestEnum.Two | TestEnum.Three};

        var serialized = Newtonsoft.Json.JsonConvert.SerializeObject(o);

        Console.WriteLine(serialized);

        var deserialized = Newtonsoft.Json.JsonConvert.DeserializeObject<TestClass>(serialized);

        Console.WriteLine(deserialized.TestValue);

    }

    public class TestClass

    {

       public TestEnum TestValue{get;set;}

    }

    [Newtonsoft.Json.JsonConverter(typeof(Newtonsoft.Json.Converters.StringEnumConverter))]

    [Flags]

    public enum TestEnum

    {

        One,

        Two,

        Three

    }

}