Diamond Pin & The Eternal Feminine

Wealthy, eccentric, inveterate practical jokester Ursula Pell has often reminded her live-in niece Iris Clyde that when she dies, Iris will inherit a beautiful diamond pin. Iris has no reason to doubt her aunt, since it is known that Mrs. Pell has a secret cache of jewels that, presumably, her few heirs will inherit. (goodreads)