Princess Sapphire and Princess Amber as well
I always think of Sapphire automatically because of that weird comic story with the pool and the helterskelter rainbow whatever it was...
I love a lot of night themed ponies, but also a lot of day themed ponies as well. Just some of the colour schemes of night-related ponies are really cool. And many have a blueish theme to the colour pallette, which I really like as well.