Brooklyn Beckham has shared an unseen photo of his fiancée Nicola Peltz's jaw-dropping engagement ring.He took to Instagram with the photo, showing the couple holding hands on a walk, and revealed a close-up of the impressive gem.SEE: Victoria Beckham confirms son Brooklyn is engaged with beautiful messageWATCH: Brooklyn Beckham gets engagedExperts had previously valued the diamond at approximately £120,000 - £160,000, after surmising that it could be a 4.5-5 carat diamond in a classic solitaire