The Kris Lees trained five year-old daughter of I Am Invincible raced up on the pace for Corey Brown and was strong to the line in beating last year's Group I Coolmore Classic winner Daysee Doom by a neck in the 1600 metre feature.
"I've had a good association with this mare, she's been good to me. I know I won a big one on her when I first arrived home from Singapore. It was good to get back on her," Brown said.
"She's been going well but she's been a little bit luckless. She's tough. Full credit to Kris and the stable, they're going really, really well."
Retained to race by her breeders, Invincible Gem is the second winner from Diamond Day, a minor winner by Marwina, whose family is barren of Black Type for five generations. Diamond Day was covered last spring by another son of Invincible Spirit in Darley shuttler Territories (IRE).
Invincible Gem has the overall record of six wins and seven placings from 23 starts with prizemoney of in excess of $800,000.
Invincible Gem is the 25th stakes-winner this season for Yarraman Park's flagship sire I Am Invincible.