How do you define a gem player?

On some occasions i've noticed gem players refeered to people like neymar or kierrison...but i define a gem player as someone who comes from a crappy team in a lower league and you can built them up into solid or quality players. The young starlets mentioned properly already have a decent future in the game.

how do you define a gem?

For me it would be someone that consistently performs better than his attributes seem to suggest.

Yeah, a young player with great potential but also pretty good already.

For me it would be someone that consistently performs better than his attributes seem to suggest.

This. I say someone who does amazing in his position. Attributes doesn't matter.