In the New Moon script, Jacob is in the parking lot. He meets Bella and Edward. He gives her a birthday present. It happens to be a dreamcatcher necklace.
Now, the bracelet, and I'm assuming you're talking about the নেকড়ে bracelet, isn't প্রদত্ত to Bella until Eclipse. For her graduation. So, NO WORRIES!
I can't guarantee that the bracelet will be in Eclipse since I don't have the script yet, but it's not in the New Moon movie because it wasn't in the book! :)
And, I'm sure they will include the charm bracelet in Eclipse. That's one of the pinnacle points in the the book. And Summit isn't that stupid to leave that out.
They should have left it a bracelet, it's আরো discrete. Bella is not the kind of girl that likes to প্রদর্শনী off and a নেকলেস is আরো obvious than a bracelet. Not to mention the diamond.
I think it's kind of silly. It's so easy to just follow the book, but they just have to change the little things. I don't understan why they wouldn't just stay as true to the book as posible.