The 38-year-old singer and songwriter is reported to have popped the question to radio DJ and TV presenter Hope, 32, back in May this year
The Cambridge alumna was first spotted wearing the luxurious diamond ring at the Chelsea Flower Show in May, next to Harris.
The Feels DJ is said to have shortly proposed to Hope underneath a tree at his Ibiza 138-acre farm, Terra Masia, where he now lives.
Despite the expense of the ring, the couple are reportedly hoping for a simple wedding on the Spanish island.
A source told The Sun: “Although it is a stunning ring and extremely expensive, the couple aren’t going for a flashy or expensive wedding.
“The extravagance of the rock will eclipse how much they’re going to spend on the big day itself as they want to keep it low key and simple with just a core of close friends and family present.”
Harris, known in his personal life as Adam Richard Wiles, has been dating the Geordie radio presenter for the past five months.
The former Strictly star has been pursued by the musician for several years, after he first asked her out when she was 19.
The radio DJ revealed on-air that she had previously rejected the Acceptable in the 80’s singer due to his younger looks – but then went on to regret the decision.
She told Capital Breakfast host Roman Kemp: “He looked how he used to look, I was shallow, I was 19, and I said no and I went off with either Scouting for Girls, or The Wombats…I thought they were going to be bigger but no, it turns out Calvin Harris was going to turn into an Adonis.”
Hope previously hosted Capital Breakfast before moving over to Radio 1 to co-host alongside Jordan North in 2021. She is also a published author and journalist.
Harris previously dated fellow musicians Taylor Swift, Rita Ora and Ellie Goulding before recently splitting with his model girlfriend, Aarika Wolf, in March this year.
Media presenter Hope last dated her long-term partner of four years, comedian Tom Rosenthal, until 2017.