I have this problem myself and from personal experience the only things that work for me are Real Gold even 10K is fine, Sterling Silver, or Stainless Steel. (even if it says hypoallergenic but is not one of the above I will have a reaction)
At 10yrs old if she likes costume jewelery she may LOVE the real stuff "like mommy has". I know I have purchased gold earrings relatively cheap (between $10 & $15), My son just bought his "girl" a bracelet in sterling for $8, and my watch is stainless (that one was a little pricey).
Try one piece to start and see how she handles the responsibility, then go from there.
Good luck.