As a foal in December 2006 she was put up for auction at Tattersalls and was bought for 700,000 guineas by Dermot "Demi" O'Byrne on behalf of John Magnier's Coolmore Stud organisation.
[3] Moonstone's dam Solo de Lune never raced but was a very successful broodmare whose other foals included L'Ancresse (second in the Irish Oaks and the Breeders' Cup Filly & Mare Turf) and Cerulean Sky (Prix Saint-Alary).
Racing on good-to-firm ground she tracked the leaders before being outpaced in the straight and finished fourth behind Lush Lashes, Cape Amber and Dar Re Mi.
[7] Moonstone was a member of a six-horse Ballydoyle contingent for the 230th running of the Oaks at Epsom Racecourse on 6 June and with Johnny Murtagh, who had ridden her in her first two starts, opting to partner Adored, she had Richard Hughes in the saddle.
[8] She was made a 25/1 outsider but after being restrained at the rear of the field in the early stages she stayed on strongly in the straight to finish second to Look Here with the favoured Lush Lashes back in fifth.
Despite her odds, Ice Queen showed no signs of weakening and it was only in the final strides that Moonstone overhauled her stablemate to win by a short head.
Three weeks later she was moved up in distance and matched against male opponents in the 3100 metre Prix Royal-Oak and produced a rather better effort, coming home sixth of the eleven runners, four and a half lengths behind her stablemate Yeats.