"It would be thick as thieves. Without question," Harry told Mishal Husain of BBC News. "I think she would be over the moon, jumping up and down, so excited for me. But then she probably would have been best friends with Meghan. So, it is days like today when I really miss having her around. I miss being able to share the happy news. But the ring and with everything else going on, I'm sure she's with us, jumping up and down somewhere."
Harry certainly had his mom on his mind when designing Meghan's engagement ring, which includes two diamonds from Princess Diana's jewelry collection, as well a main stone from Botswana.
"The little diamonds on either side are from my mother's jewlery connection to make sure she's with us on this crazy journey together," Harry explained.
And Meghan, 36, isn't taking the gesture lightly.
"I think everything about Harry's thoughtfulness and the inclusion of that, and obviously not being able meet his mom, it's so important for me to know that she's a part of this with us," she said.
Meghan also noted that she's been able to spend time with people who were close to Diana.
"I think that being able to meet his aunts and also [her close friend] Julia, and just different people who were so important to his mom, I'm able to in some way know a part of her through them, and of course through him," Meghan said. "And it's incredibly special to be able to have this [her engagement ring] that sort of links where you come from, and Botswana, which is imporant to us. It's perfect."
As for Harry's family -- including his father, Prince Charles; his brother, Prince William; and his sister-in-law, Kate Middleton -- Harry says they were nothing but supportive of his relationship with Meghan.
"It was exciting. I mean, I'd been seeing her for a period of time, where I literally didn't tell anybody at all," Harry said about introducing Meghan to his family. "And then, William was longing to meet her and so was Catherine -- they're our neighbors -- we managed to get that in a couple of times now. Catherine has been amazing."
"The family together has been an absolutely solid support," Harry continued. "And my grandparents, as well, have been wonderful throughout this whole process, and they've known for quite some time, so how they haven't told anybody is again a miracle in itself. But, the whole family has come together and has been a huge amount of support."
As for Meghan's family, she admitted her parents and close friends were "concerned" at first about their relationship.
"[The relationship] quickly set up a media storm that was not a part of my life before," she admitted. "But, they also had never seen me so happy, and I think also once my friends were able to really meet Harry, and my mom, who we spent a lot of time with, it was so much fun."
"Her mom is amazing," Harry echoed.
Meghan's mom, Doria Radlan, spent time with the couple during the Invictus Games in September. On Monday, Meghan said Harry has yet to meet her father, Thomas Markle.
"He's talked to my dad a few times," she shared. "Hasn't been able to meet him just yet. But, it's all been worth every effort."
On Monday, Meghan's parents sent out a statement about their daughter's engagement.
"We are incredibly happy for Meghan and Harry," the statement reads. "Our daughter has always been a kind and loving person. To see her union with Harry, who shares the same qualities, is a source of great joy for us as parents. We wish them a lifetime of happiness and are very excited for their future together."
For more on Harry and Meghan's engagement, watch the video below: