string GetColorName(Color color)
{
    var colorProperties = typeof(Color).GetProperties(BindingFlags.Public | BindingFlags.Static)
                                       .Where(p => p.PropertyType == typeof(Color));
    foreach (var colorProperty in colorProperties) 
    {
        var colorPropertyValue = (Color)colorProperty.GetValue(null, null);
        if (colorPropertyValue.R == color.R  && colorPropertyValue.G == color.G 
         && colorPropertyValue.B == color.B)
        {
            return colorPropertyValue.Name;
        }
    }

    //If unknown color, fallback to the hex value
    //(or you could return null, "Unkown" or whatever you want)
    return ColorTranslator.ToHtml(color);
}