The correct spelling is Kastehelmi. Some of the range (bowls and plates) is still being made today by Iittala (who took over Nuutajaarvi) in clear, light blue and apple green.
I think your candleholder is blue rather than turquoise. This colour seems to have been withdrawn in 1973. See
here. All the range isn't shown.
The colour M is thinking of is shown here
here