01

What to look for

Under 10x loupe: long thin hollow channels running parallel to each other and to the crystal growth axis. In aquamarine they look like falling rain. In chrysoberyl they can create the cat's eye effect when dense and aligned.

02

What it means

Parallel growth tubes in aquamarine are diagnostic. In chrysoberyl, aligned tubes can create chatoyancy.

03

Expert move

For cat's eye chrysoberyl, hold a point light source above the stone and rotate. A sharp, centered eye indicates fine alignment.