Hi Joanie, If you mean the original blue/grey (now just called Grey) rather than the more vivid blues, the code number was and is, International 289. From what I've noted over the years, this seemed to be the most popular colour.
As it happens, I finished doing my decks with 289 yesterday!
The other current International blues are Squall Blue (923) which is more turquoise or Pale Blue (339) which is actually a lot darker than Squall!!
You should be able to get all of them in any chandler.