That's the card I thought of after you said stuff. I don't know why you thought I knew whether or not mail-mi had it, when you were the only one with that information.
Here is how you could have known the result:
sudgy - you know you don't have it
TA - you asked him, if he had green solitaire - he had none
Nkirbit - I asked him, if he had diamond solitaire - he had none
GOM - mail-mi asked me, if I had green solitaire - I had none
That leaves mail-mi: you asked him, if he had green opals. Hence you knew that he has at least one green solitaire (the green opal solitaire, he showed you). After my last question, you could deduce that he had no other green solitaires, hence nobody has the green diamond solitaire.