private static Hashtable ITEM_GEM_DISPLAYNAME = new Hashtable(){
            {<itemIDOfnormmoon>, "Normal MoonGem"},
            {<itemIDOfrefmmoon>, "Refined MoonGem"},

        };


//Then you can access that:

Client.Log(ITEM_GEM_DISPLAYNAME[<itemIDofNormMoonGem>]); // Will display Normal Moon Gem


//You can use this hashtable for all your Gems and Items to set a Display Name :)