Thanks for your responses. As I mentioned in my OP this was part of how we were addressing it, I wasn't just sitting her down and saying 'don't be sad - look at these shiny reasons not to be'. Dd's main issues are about connection and lack of a sure shelter to use one of Miraca Gross' terms. She's loved being quirky and different for the most part, but she's a couple of years in to her skip and it's now run out of juice socially - for now she just feels too odd.
So to address thisI have school meetings booked, I'm finding her a mentor in her preferred topic, we're looking at new extra curricular stuff to meet some new people, I've got her thinking about it being possible to have different friends fir different purposes and so on. But dd is so angry about her difference at the moment and while we have found the gifted label a useful one for proving context to her experience of difference and the parts of life that have been difficult for her (and each to their own on that one - I know some people feel passionately about never using the 'g' word with their children but it has been useful for us), giftedness is a wholistic thing in itself and comes with benefits too (we too discussed choices, along with humour, ability to access and understand exciting and great ideas, the great gift of not having to struggle with some life skills like general math and reading, about being able to problem solve at a high level). Dd was only seeing those bits that of being gifted that were problematic - that it is hard to find friends with common interests (and while I've let her know this can change as you get older, that doesn't help her right here and now), hard to stay switched on at school, having to be the odd one out all them time (one of the benefits of being a gifted adult is you can blend into the crowd sometimes if you want to - for dd, she's always the youngest in class, always the smartest in class - always representing 'something' for so many hours of the day and while 99% of the time she's happy being quirky and odd and is accepted as such, sometimes she doesn't have the emotional energy for it and she'd just like to be 'one of many'). So in amongst many other approaches to dealing with this particular rocky patch, I was looking to reframe her current thinking about being gifted. Thanks again to those who shared their ideas, I will share them with her.