There are distinct two variations of this set, one is printed on white card and the other on cream card, although there is a wide variation of tones between the two also available. This is particularly noticeable on the text side of the cards.

It is also possible to find paper thin cards for this set, typically the following cards; 1,2,3,5,8,10,12,14,17,19,21,22,24,25,26,29,32,37,41,42,44,46,47,48,49
please see an article here.

The text printing on the back of the cards is blue on all variations.