It does exist and is being held and locked up tight by those whom own it.
Along with many other items, there was a bug way back that allowed people to transfer off of test center for a very short period of time.
You will notice test center items in various people collections. I know this is a source of a few different hued clothes (including glacial) there are other odd ball hues out there too. Over the years certain devs have had numerous dye tubs that allowed you to enter the hue IDs and players could dye anything any hue available in game.
If there were other methods to the cloths creation id love to hear them.