That Green crystal looks like the one in Superman 2, the one that Superman hands to Lois inside the fortress. I have been looking for that colour of acrylic to make my own crystal but cant find none!!!
That is very cool looking. Although it is listed as a piece of kryptonite. I think it's more one of the crystals. The only kryptonite seen in the movie was a rock. And as for the crystal, a friend of mine and fellow Superman fan has a very realistic looking one. The caption has has for it on his Facbook profile is the "Brando Krypton Crystal". I'll have to ask him where he got it.