https://www.popularmechanics.com/science/environment/a29401027/matryoshka-diamond/
This Is the World's First Diamond Within a Diamond
Russian miners unearthed a gemological oddity—a type of rare diamond called a Matryoshka diamond. It is thought to be the only one on the planet and the first of its kind, but has not yet been assigned a monetary value, according to a statement.
Named for the famed Russian nesting doll toys, the Matryoshka diamond is a tiny, tabular-shaped diamond encased within a larger diamond. Incredibly, there is enough space within the larger diamond, that the smaller specimen rattles inside, the report said. The outer gem is roughly .62 carats, but the inner gem is much smaller, weighing only about .02 carats. '[snip]
