Are you a YGO collector? If so, I have some items that you might be interested in (unvarnished printers-proof cards, for instance).
Anyway, my gem would probably be my no-rarity-symbol Japanese Base Set Pikachu autographed by Ikue Otani (the actress who voices Pikachu). Of course, most other collectors are more interested in my Tropical Mega Battle No. 1 Trainer.
Nah, I have one deck that I created before the XYZ formation and they had blue eyes white dragon in them.
I used to play Yu-Gi-Oh in 2003 then stopped, I just played a few months back while at work since he was still playing and I still have my old deck, and some guy had some synchro crap deck, by the new standard it was good but from someone who played since YuGiOh came out it was utter stupid, he literally took 4 minutes in one turn looking for cards, removing them, returning them from the graveyard, then destroying his own cards to bring out 1 of his new cards which I stopped with a man-eater-bug, then I summoned a Dark Magician and beat the crap out of him… new advanced format is retarded.
My Gem has to be my 1st edition Japanese Mew Ex, signed by the illustrator himself!
i1289.photobucket.com/albums/b517/decocqvandelwijnen/2013-10-09222556_zps83122b43.jpg
He is indeed a very good artist! and no unfortunately I didn’t get it in person. But I’m in contact with him and he sent me 4 signed cards with a letter 
My gem,
he’s a little old and used, (not by me its how i got him) but he’s my favorite card
i had other favorites but he’s my most favoritestestestest
That’s a really tough question; I actually have two favorites… The first is a PSA Gem Mint 10 “d” Ed. Butterfree (designated as “d” Ed.). The second would have to be one of each cover art (3 Total) 1st Ed. Chinese Base Set 1 booster packs
