The ring is a thin silver band with a single oval diamond.
Exact details about the ring were not immediately available, but diamond expert Steve Stone told the Daily Mail that it's likely worth about $1 million. Mike Fried, another diamond expert, told Hello! that the rock is likely "larger than 15 carats" and worth about $1 million.
This will be the first marriage for Kourtney, 42, and it comes after a long relationship with Scott Disick, whom she broke up with early this year. She and Disick had three children together and he reportedly wanted to propose to her but she discouraged it.