If you have done any of the side quests with Triss, you can't show her Phillipa's crystal.
Has anyone done Radania's most wanted before any of the Triss quests & knows what happens if you show her the crystal?

I feel with you. I got the same problem, i have a megascope crystal and a magic doll (the second i found).

Had the same problem. Just don't finish this quest yet, you'll be able to show Yenn the crystal instead later in the game.

Have you done that?
I read in on the net & went to Skellige, with the Redania's most wanted quest active & I never got the option to show it to Yennifer.

I've since gone back about 6 hours of gameplay, to before I did any Triss quests, so I should be right this time.

Yes, i could talk to her about it in the inn she stopped in Skellige after finishing few Skellige main quests.

Dam, sounds like I gave up on it a bit too soon.
What does she say about it, & how does it effect the quest?

I don't remeber exactly but it was sth like this:

She checks the crystal and finds out (with the power of MAGIC of course) that Phillipa is trying to grow back eyes and rebuild the Lodge. Then i had the choice of giving the crystal to Yenn or Radovid (she says that giving it to Radovid is a very bad idea). I gave it to Yenn and later had to go to Radovid anyway to tell him what i found out and iirc he didn't belived me because i had no proof.

Thanks Ukis.
In my first playthrough, where Triss had already gone to Kaer Morhan by the time I got the quest item, I never gave the Cyrstal to Radovid because I thought I might have been able to get Phillipa on side to help at Kaer Morhan.
So the only difference is the red, failed line.

On my 2nd play through I tried to show it to Triss while she was still in Novigrad, but in the many times you talk to triss in Novigrad, it just doesn't give you the option to show it to her, & the after the witch hunters are outside Triss's house you get quest failed, in red.