Jenna Dewan's engagement ring was designed to "echo the cosmos".

Jenna Dewan and Steve Kazee

Jenna Dewan and Steve Kazee

The 'Flirty Dancing' star got engaged to her partner Steve Kazee - with whom she is expecting a baby - earlier this week, and he has now opened up on the process of designing her engagement ring, for which he enlisted the help of actress Nikki Reed and her sustainable jewellery brand BaYou With Love.

Steve explained on his Instagram Story: "When I first started to look at engagement rings for Jenna, I knew I wanted something unique. It had to be unique. It had to be representative of who Jenna is. It had to be as beautiful as her.

"[When I turned to Nikki, I] instantly knew that I had found the right person to help create the ring! Nikki came in and talked to me about what was important to me and shared her immense knowledge of jewellery design and sustainability in the process."

The Tony Award-winner also spoke about the special meaning behind the ring, which was designed with the "universe" and the "pleiades constellation" in mind, as it holds "special meaning" for the couple.

Steve said: "[The design is] based around my desire to have it echo the cosmos.

"The solitaire is representative of our oneness in the universe surrounded by stars. The diamonds laid into the band are representative of the pleiades constellation which holds special meaning for Jenna and I."

Meanwhile, 'Twilight' star Nikki recently revealed her involvement with the process when she congratulated the couple on their happy news.

Taking to her Instagram Story, Nikki said: "An honour to be a very small part of this special moment.

"I love you both, and all I can say is your love is pure magic.

"I might be biased but that ring is gorgeoussssss! Steve, making this with you was such a beautiful experience. Thank you for loving Jenna the way you do. (sic)"

According to ring expert Kathryn Money from Brilliant Earth, she estimates that the centre stone is 3.5 to 4 carats and set on a delicate gold band.

Depending on the quality and characteristics of the gemstone, it's estimated somewhere between $50,000 and $80,000.