This isn't the first time Pia has fuelled secret wedding rumours.
Back in January, the actress was spotted wearing a silver band on her ring finger in Sydney and in March she rocked a diamond version whilst holidaying in Mexico that she wore with her dazzling engagement ring.
In a chat with Daily Mail Australia, 77 Diamonds managing director Tobias Kormind revealed the eye-watering estimated cost of Pia's engagement ring.
“From Pia Miller's celebratory Instagram post, her ring looks like a 10 carat to 12-carat solitaire oval diamond, set in a platinum band, which would be priced at between US$800,000 (AU$1.10million) to US$1.4million (AU$1.9million),” Mr Kormind said.
Patrick, who is the CEO of Hollywood talent agency WME (who represents the likes of Matt Damon) and is estimated to be worth US$440million (AU$630million).
Pia and Patrick were first linked in May 2019, less than a month after Patrick's divorce with ex-wife Lauren Sanchez was finalised.
The couple then made their public debut in October of that year at a Los Angeles Halloween party.
Due to the coronavirus pandemic border closures, however, Pia and her man were separated - whilst Pia was in Sydney, Patrick remained in the US.
They were then reunited in September.
In March, mum-of-two Pia threw an extravagant birthday bash for her son Isaiah Powell's 18th birthday.
According to a report by The Daily Telegraph, the model and actress spent $25,000 on a private jet to take Izzy and his pals from Sydney to Melbourne. The birthday bonanza was then held at the rooftop bar of Le Ciel, a luxury event space with a breathtaking view of Melbourne’s CBD.
Pia, who is also mum to 14-year-old Lennox, even gifted Isiah a luxury car for his milestone day.
“EIGHTEEN years of loving you,” she wrote in the caption as Izzy was seen grinning from ear-to-ear in front of his new SUV. “Happy birthday beautiful.”