If you already have a BJ Birkin, I would go for a different bag in turquoise or even an accessory. I'm a little biased towards the turquoise accessory - I love my turquoise Bearn! I would branch out a bit, JMHO.
I love turquoise, especially in swift. It is a very saturated "wow" color, that works better for me than BJ. I also love the black edges.
i'm not nuts for turquoise, but as others have said it is totally fab in swift.