Diamonds occur in many crystal shapes. The octahedron is the most commonly used because it readily lends itself to being cut into the traditional round brilliant shape we are most familiar with.
These crystals were sawn in half preparatory to being cut into finished stones. I was able to buy them before any faceting began. I like the pyramidal quality and love how they look in groups, somewhat like mountains. This is my take on the classic diamond circle earring.