using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var config = new Config()

        {

            ID = "8",

            Name = "floating-point",

            Colour = "getColour('floating-point')"

        };

        var json = JsonConvert.SerializeObject(config);

        Console.WriteLine(json);

    }

}

​

public class PlainJsonStringConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return objectType == typeof(string);

    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        return reader.Value;

    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        writer.WriteRawValue((string)value);

    }

}

​

public class Config

{

    public string ID { get; set; }

​

    public string Name { get; set; }

​

    [JsonConverter(typeof(PlainJsonStringConverter))]

    public string Colour{ get; set; }

}