Very well done on the 3D mesh here! I think the Ambassador originally had a red impulse engine, though; that aside, you've done a great job! Keep it up!
The Enterprise-C, the first appearance of the Ambassador class ship, consistently had a blue impulse engine.
This is a beautiful model! I guess she was named after an ancestor of the Admiral Nakamura we saw. He'd have been a baby when this one was commissioned...