How long should you be in relationship before you buy your girlfriend jewelry

I think gifts should be given whenever you feel compeled to give one. Some questions you could ask yourself are... Does she have the same feelings of affection that you have for her? Will the gift be to expensive (you would never want to regret giving it if it didn't work out with her) Finally, I must tell you, if this is a ring, wait until you have talked about a long term relationship with each other. It could scare her if it is given to soon. Good Luck.
You can feel free to give more info. i.e. how long have you been dating. What sort of jewlery. How old you are.

Also, keep in mind that your partner might leave one day and take that gift with them.

I gave my ex a $1000+ necklace and well... she is an ex now with a pretty necklace.

Only when it has been a full moon 4 times... and you see venus in the sky.
Seriously? Whenever you feel like it.

If she's already your GF then you've already made a commitment to each other , so buy away in my opinion.

The choice is yours but if she just became your girlfriend recently you don't want to get her something expensive right away. Something simple that shows that you were thinking of her is a good idea.

When it feels natural and real and you want to give it from your heart.