Something for a younger woman! ;-)
No-one likes to think that they are seen as old - even if they feel it.
You gift must obviously be based on what you can afford, and also on the closeness of your relationship with this lady.... so there is no 'right' answer going to come from the people here.
Buy her something which furthers an interest she already has - books if she's a reader, household art (paintings or ornaments) if she's into that, or even a hamper of strange or exotic food if she has a healthy appetite for the pleasures of the table.
The perfect birthday gift to give to a 42 year old woman that has everything is something that could be experienced. For example, the woman may enjoy going to lunch and a movie, or getting a manicure and pedicure.
Your presence is the best present for a 100 year old woman.
a 27 year old woman.
The best birthday gift you can get a sixteen year old is money. A better gift would be to buy them their first car.
A car.
A poo!
Sticky Kicks of course! hands down, the best gift ever! totally unexpected yet so personal!
A webkinz, charm braclet, ECT
It really depends on what your girlfriend likes. Earrings? Music?
Good part of a thoughtful gift would be some jewelery, chocolates (a mix of something that she can enjoy/ consume at the moment and something that will remain). I found that artwork is tasteful and thoughtful gift. I do not know any woman who would not like Kristine Stranga's collages.
A nice gift for a seven year old girl's birthday might be a pretty locket. She will treasure this nice gift and be old enough to understand the meaning behind it when a special picture is put in the locket.
My go-to gift for a woman at any age is Vera Bradley.