The Queen's Diamonds, Hugh Roberts, Royal Collection Publications, 2012, was published to mark the Diamond Jubilee of Queen Elizabeth II (referred to by me in this subthread as The Queen).

Roberts introduced the expression 'Heirloom of the Crown', which I thought was an excellent way to identify many of the jewels and where they belonged.

I felt that Roberts used the expression only where there could be no doubt. For some other jewels I felt he handled their "belonging" quite deftly because the matter was not clearcut or maybe disputed.