Its my dds 1st birthday on mon and we were given some money from my grandma and her great grandma.....she sadly passed away on weds and I really want to buy dd something with the money that she can keep forever and know that it was from her great grandma....but i'm stuck!
So sorry to hear about your loss. What a lovely idea to buy a keepsake. I'd suggest a piece of jewellery, perhaps something you pass to her when she's 18 (and old enough to look after). A locket, perhaps, with a pictures of her great grandma in it? Just thinking that's the sort of thing your grandma might have bought for her?
Or is there something that her grandma loved (a place, gardening, something like that) that you could buy a book about, and put a message of why it was chosen, with a picture of Grandma in said place/garden/etc inside?
Lockets, charm bracelets, etc are pretty timeless though and most people keep them regardless of fashion.
If you or your family have them, what about getting copies of family photos from as far back as they go and making up an album? That would be nice. I know what you mean about trends changing, but that's likely to be true of anything you buy. I suggested a locket, because even if it is old fashioned, it's the sort of thing your Grandma might have bought. If there is anything which actually belonged to your Grandma which you could put away for her, that would also be good.
[warning - this may sound awful, but between me and DH we've done far too much of this sort of stuff so don't dismiss it out of hand]
I wouldn't buy jewellery till you know great-grandma hasn't left dd anything of hers - whatever you buy she won't appreciate it just yet (esp if you're keeping it till she's 18), and once the wills etc are sorted out you may find that there was something specific she wanted dd to have.
Buy DD a little something nice for her birthday but don't make any heirloom / investment type purchases till probate's been granted and you know where you stand.