One of the more subtle inclusion scenes gemologists sometimes observe in natural diamonds is the presence of crystallographically oriented structural defects known as “internal graining.”

Remarkable “horsetail” inclusions discovered in a demantoid garnet, while their origin and composition remain under discussion.

Nacreous pearls are known to have platelet growth resembling fingerprints or topographic maps, but a less common appearance is nacre with a concentric spiral pattern.

Analysis of a transparent yellow angular crystal inclusion in a Brazilian rock crystal quartz host suggests monazite.