give her the d

if you 2 are not dating each other, gifting might be awkward, and a ring might be too "romantic" which is easily understood
if I would want to gift something to someone I like, i would probably invite on a date, or to do an activity that she likes
money does not give happiness, you do

good luck, cheers!

I like her, and she likes me. I'm planning to ask her out on Saturday... which would mean we would be going out for 10 days until Christmas. (ik it may be a bit much, but still)

I understand a ring may be too much, but is a ring that much different than any other piece of jewerly? I want her to know that i care about her... unless you're sure a ring brings across that kind of message? (Thanks btw.)

The birthstone is a pretty good idea, but the ring isn't. Rings tend to be associated with strong commitment, and after only being together 10 days, it would most likely be a bit much. See what you can do in terms of a necklace or bracelet with her birthstone, not something too expensive, but not something that looks cheap either.