Meg and the Disappearing Diamonds by Holly Beth Walker, 1967.
Margaret Ashley “Meg” Duncan lives in a small town called Hidden Springs in Virginia, not too far away from Washington, D.C., where her father works. Her mother is dead, and she has no brothers or sisters. When her father is away in Washington, working, Mr. and Mrs. Wilson, the gardener and housekeeper, take care of her. For company, Meg has her beloved cat, Thunder (who doesn’t like anyone but Meg), and her best friend, Kerry.
People in Hidden Springs have been talking lately about Mrs. Partlow and her diamond jewelry. Mrs. Partlow is the wealthiest, most important woman in town. Usually, she keeps her jewelry in a vault at the bank, but recently, she brought them to her house so that she can wear them at her niece’s wedding. Then, someone attempts to break into Mrs. Partlow’s house. Nothing is taken, but everyone can guess what the thief was after.
Mrs. Partlow invites a few friends to her house for tea to show them her jewelry and thoughtfully invites Meg and Kerry to join the women. Meg and Kerry are excited at the chance to attend a grown-up tea party and to see Mrs. Partlow’s fabulous jewelry. However, the party is crashed by Mrs. Glynn, a new woman in town. Mrs. Glynn has three trained dogs that she dotes on. She dresses them up in fancy costumes, and she can’t resist the opportunity to show them off when she wanders into the gathering in Mrs. Partlow’s garden. The dogs cause a disruption, and after it’s over, everyone realizes that Mrs. Partlow’s diamond jewelry is missing!
Could the dogs have been an intentional distraction? What about the person who tried to break into Mrs. Partlow’s house earlier?
Kerry’s much younger cousin, Cissie, is visiting her family and has a habit of taking things that catch her eye and hiding them in her secret “playhouse” which changes locations from time to time. So far, the girls know that she’s taken Meg’s ballet slippers. Cissie also slipped into Mrs. Partlow’s party, uninvited and unnoticed by the other guests. The girls don’t know for sure that Cissie took the jewelry, but the theft is a serious crime, and they don’t want to see little Cissie get into trouble. They have to either find Cissie’s new “playhouse” and search it for the jewelry or to discover who else might have taken the diamonds before anyone else realizes that Cissie might be the thief.
My edition of the book has drawings that are done in kind of a gray green color.