here's a closeup of the coral. doesn't look a whole lot different than what you have there.
as for the growth pattern, i've seen 2 pieces from the same colony look all together different in 2 different tanks.
as far as the color goes, this was the very bottom of a colony about 3 times this size. the shaded areas are the ones that have lost the purple.
i don't know if they will ever color back up, but i think any new growth will be purple.