Ruth Davis, FGA DGA, the head of jewelry at Scottish auction house Lyon & Turnbull, poses with the Abernethy Pearl in a shell. The pearl is expected to be the highlight of Lyon & Turnbull’s “The Cairncross Collection” jewelry auction, scheduled to take place this Wednesday, Aug. 21. (Photo credit: Lyon & Turnbull/Stewart Attwood)

The Abernethy Pearl in loose form. William Abernethy found the pearl that bears his name in 1967. It could have been growing in its mussel shell for more than 80 years prior to its discovery, meaning it began forming sometime during the reign of Queen Victoria (1837-1901). (Photo credit: Lyon & Turnbull/Alex Robson)