1143 GMT December 16, 2018
CCTV images show the romantic proposal going wrong and the pair unsuccessfully trying to retrieve the piece of jewelry, BBC wrote.
After seeing the footage officers managed to rescue the ring, clean it up and now want to find its owners.
They have put out a plea for the man and woman to come forward.
The footage was taken just before midnight on Friday night and was released by police shortly after.
It doesn't show the moment the man pops the question but we do see him getting down on one knee in an attempt to find the ring.
His fiancée (although we don't know if she actually said yes) puts her hands to her face when she realizes what has happened.
She crouches down next to him, trying to help but they are unsuccessful.
The man then lies down on the floor by the grate, trying to reach the piece of jewelry but again they are unable to retrieve it.
The good news is that officers from the New York Police Department clearly have a romantic side and, more importantly, access to the grate, so could get it out quite easily.
As well as the footage of the couple they released an image of the cleaned-up ring on their Twitter account with the caption: "Here's a photo of the ring our officers recovered (and cleaned!) Call 1-800-577-TIPS or DM @NYPDTips if you know the happy couple so we can return it to them!"
Sadly, staff at the NYPD Deputy Commissioner's Office say nobody has come forward yet but they are hoping to reunite the couple with the ring and find out if she actually did say yes.