He kept the caption simple with a double heart emoji.
Though diamonds may be a girls' best friend, Emma's engagement ring is unique with a gorgeous pearl set in what appears to be silver or white gold.
Stone and McCary have been dating for over two years.
The Golden Globe victor opened up about her thoughts on marriage and kids in an interview with her BFF Jennifer Lawrence for Elle magazine in August 2018. The couple reportedly met in 2016 when the 31-year-old hosted an episode of the show.
Australia vs Pakistan - Highlights & Stats
Pakistan batsmen spent most of their time performing damage control, as Australia won both matches without breaking a sweat. The sixth-wicket pair offered some stubborn defence before Lyon had Iftikhar Ahmed (27) caught by Labuschagne at short leg.
While Stone and McCary are relatively private about their romance, the duo have been spotted together multiple times and enjoyed a date night in New York City in April, heading out for dinner in the city after SNL rehearsals.
The two have been going strong since the past two years as they began their relationship after meeting on SNL in October of 2017. "As a teenager, I was like, "I'm never getting married, I'm never having kids", she told the magazine. "And then I got older and I was like, I really want to get married, I really want to have kids".
He also accompanied Stone to the 2019 Screen Actors Guild Awards last January when she was nominated for for her turns in "The Favourite" and the Netflix series "Maniac".
The pair split in 2015 after nearly four years together.