In her will Princess Mary, Duchess of Gloucester bequeathed an amethyst box (which she called a bon bon box) to Princess Mary of Cambridge, mother of Queen Mary.
Mary, Duchess of Gloucester described the box as having been made of the root of an amethyst with diamonds & rubies on the lip of the box.
I never expected to see an image of the box but it is in the Royal Collection having eventually come into the possession of Queen Mary.
The mystery arises because Queen Mary, after perusing the sales catalogue of items belonging to Queen Charlotte, which were auctioned on 18 May 1819, believed that the description of a snuff box matched that bequeathed by Mary, Duchess of Gloucester to Mary Adelaide, Duchess of Teck.
The descriptions of both items are slightly different, which is probably why the Royal Collection site commented that Queen Mary was probably optimistic in her conclusion.
In addition, the Duchess of Gloucester in her will gave provenances for many items. She stated that the box she gave to Mary Adelaide, Duchess of Teck had belonged to her sister, Princess Sophia.
I was very taken with the image of the little box. Because the Duchess of Gloucester had described it as a bon bon box, I had assumed it was a larger item. The size of this little gem suggests that the Royal Collection site's description of the the box as a snuff box is more accurate.