using System;

public class Program

{

    public static void Main()

    {

        Foo foo = new Foo { Bar = "\u001d" };

        string json = Newtonsoft.Json.JsonConvert.SerializeObject(foo);

        Console.WriteLine(json);

        DumpCharsAsHex(json);

        string json2 = RestSharp.SimpleJson.SerializeObject(foo);

        Console.WriteLine(json2);

        DumpCharsAsHex(json2);

    }

​

    private static void DumpCharsAsHex(string s)

    {

        if (s != null)

        {

            for (int i = 0; i < s.Length; i++)

            {

                int c = s[i];

                Console.Write(c.ToString("X") + " ");

            }

        }

        Console.WriteLine();

    }

}

​

public class Foo

{

    public string Bar { get; set; } 

}

​