Create a custom type:

public enum TColorType
{
  Red,
  Green,
  Blue,
}
 
public class TColor
{
   public string Name { get; set; }
   public TColorType Type { get; set; }
}

Create a color list:

using System.Linq;  // Required for 'Where' lambda/linq statements
using System.Collections.ObjectModel; // Required for ObservableCollection
 
public class TColorList: List<TColor>
{
    ///----------------------------------------------------------------------------------------
    /// Constructor
    ///----------------------------------------------------------------------------------------
    public TColorList()
    {
       PopulateList();
    }
 
    ///----------------------------------------------------------------------------------------
    /// Populate list
    ///----------------------------------------------------------------------------------------
    private void PopulateList()
    {
       Add(new TColor() { Name = "Red",   Type = TColorType.Red   });
       Add(new TColor() { Name = "Green", Type = TColorType.Green });
       Add(new TColor() { Name = "Blue",  Type = TColorType.Blue  });              
    }
 
}

Create a color collection:

public class TColorCollection: ObservableCollection<TColor>
{
    ///----------------------------------------------------------------------------------------
    /// <summary>
    /// Indexer overload. 
    /// </summary>
    /// <param name="aColorString">Color (string)</param>
    /// <returns>TColor</returns>
    ///----------------------------------------------------------------------------------------
    public TColor this[string aColorString]
    {
        get { return this.Where(n => n.Type.ToString().ToLower() == aColorString.ToLower()).SingleOrDefault(); }
    }
 
    ///----------------------------------------------------------------------------------------
    /// <summary>
    /// Indexer overload. 
    /// </summary>
    /// <param name="aColor">>Color</param>
    /// <returns>TColor</returns>
    ///----------------------------------------------------------------------------------------
    public TColor this[TColorType aColorType]
    {
        get { return this.Where(n => n.Type == aColorType).SingleOrDefault(); }
    }
 
    ///----------------------------------------------------------------------------------------
    /// Constructor
    ///----------------------------------------------------------------------------------------
    public TColorCollection()
    {
       PopulateCollection();
    }
 
    ///----------------------------------------------------------------------------------------
    /// Populate collection
    ///----------------------------------------------------------------------------------------
    private void PopulateCollection()
    {
       Add(new TColor() { Name = "Red",   Type = TColorType.Red   });
       Add(new TColor() { Name = "Green", Type = TColorType.Green });
       Add(new TColor() { Name = "Blue",  Type = TColorType.Blue  });              
    }
}