Sisters of Glass, by Naomi Cyprus

Sisters of Glass, by Naomi Cyprus (HarperCollins, Nov. 2017), is a good pick for fans of middle grade revolution fantasy, a sub-genre I've just coined for myself in which the young protagonists lead the oppressed against tyranny (having just now thought of this subgenre, I haven't gotten a lot of examples together yet, just Westmark by Lloyd Alexander, and Lian Tanner's books, but I feel there are quite a few...).  Neither of the two heroines of this particular book imagined that they would be leaders of a revolution in a world full of magic, where the elite bend material things into enchantments.  Nalah has no idea this destiny awaits because she's from a different world altogether, in which magic is forbidden, which is horrible for her because she's fizzing with it, putting herself and her father in great danger, Halan because she's the pampered princess, only child and heir, and doesn't know the horrible details of the kings oppression.  She just knows that she's bored and tired of being a failure for not having any magic of her own.

But when Nalah crafts a magic mirror, and steps through, she finds that Halan is her twin on the other side, in a world that mirrors her own where her magic can flow freely.  And Halan, who's snuck out of her comfortable cage in the palace, only to be captured by the rebels who are fighting against her father's cruelty, has to decide if she's going to help this strange twin....or support her father.

So of course, this being a classic mg rev. fant, as it were, Halan ends up leading the rebellion (a rather brisk and successful one) and Nalah must then decide whether or not she will stay in the world of magic...

This is a good story, but I had a heck of a time getting into it.  The two girls don't meet until just before page 200, which is a lot of set up before things start actually happening.  I'm glad I pushed on through, because once the two girls meet, there's action and adventure, and plots and magic, and I found myself enjoying it lots.   But half the book for set up really is an awful lot; I loved the craft based magic, and so I stuck with it primarily for that.  And though I then enjoyed it, the resolution seemed almost too quick and easy, and the world building was a little bit throw in the middle of it all.  But for the sake of how quickly the last 100 pages turned, I feel I can recommend it, with just a bit of reservation.  After all, not many books have glass falcons made by the heroine coming to life, and I'll read a lot for a glass falcon....

Kirkus is more enthusiastic than me, so go read their review if you have doubts.

complaint about the cover-the two girls are supposed to be essentially identical, details of hair cut aside, and both dark haired.  Why then is the princess one blond?