The couple, who are currently holidaying in the Bahamas, was spotted yesterday with 21-year-old Baldwin sporting a huge oval diamond ring.
People were quick to note that Baldwin's new bling looks similar to Blake Lively's engagement ring to Ryan Reynolds - and it might not be a coincidence.
Lively received her 12-carat Lorraine Schwartz ring, which features a pink oval cut diamond is set in rose gold with pavé diamonds around the band, from Reynolds ahead of their 2012 wedding.
And way back when the Gossip Girl actress debuted her massive sparkler, Baldwin retweeted this: "If my ring isn’t as big as Blake Lively’s I don’t want to get married."
Looks like she got her wish!
"Justin decided to propose to Hailey in front of a group of people in the Bahamas, but had been planning to ask her for a couple weeks now," a source told Entertainment Tonight.
"The ring is gorgeous and Hailey is over the moon with joy. The two can’t stop telling their friends and family how excited they are for their journey together. The two have always had a great bond, and it is stronger now than ever."