George Naoupu was identified as the stand-out player for September, having played in four out of five RaboDirect PRO12 games during what was a tough month for Connacht.
The New Zealander touched down in both the away win over Zebre and the memorable home victory over European champions Leinster in late September.
Against Leinster, the 6ft 4, 112kg number 8 secured the bonus point for the province when he crashed over the line after a remarkable one-handed carry up the touchline.
When Connacht travelled to Scotstoun Stadium to take on Glasgow Warriors, Naoupu, who currently has 38 caps for the province, move from his regular number 8 position into the second row.
Head coach Eric Elwood praised the big forward at the time, declaring: "George had one of his best performances of the year to date. He led by example in the pack through his immense work-rate and brought his trademark physicality and ball-carrying abilities to the game."
Speaking after the announcement of this month's award winner, Elwood said: "George is a strong and natural leader in our team. He is a phenomenal ball carrier and shows an exceptionally high work-rate game after game.
"His outstanding and consistent performances throughout the month of September make him well deserving of this award."
Naoupu himself said: "I'm absolutely delighted to receive this award, it's a huge honour to be chosen as the Player of the Month for the start of the season.
"We're all working extremely hard as a team and it's nice that this award is in place to recognise that effort."
Richard Hartmann, director of Hartmann Jewellers, spoke about the collaboration. "Hartmanns of Galway are very excited about the continued partnership for the 2012/13 season; it provides us with a unique and innovative way to interact with Connacht Rugby and align both brands," he said.