Serializing dictionary to string

DictionaryToString.cs

public static string DictionaryToString(Dictionary<string, string> d)
{
    // Build up each line one-by-one and then trim the end
    StringBuilder builder = new StringBuilder();
    foreach (KeyValuePair<string, string> pair in d)
    {
        builder.Append(pair.Key).Append(":").Append(pair.Value).Append(",\n");
    }
    string result = builder.ToString();
    return result;
}