Snowflake simple crystal. Light micrograph of a simple prism snowflake, part of a diamond dust crystal set. These tiny snow crystals look like sparking dust in sunlight. They are the smallest snow crystals, many no larger than the diameter of a human hair. Snowflakes are symmetrical ice crystals that form inside clouds when water vapour condenses directly into ice. The exact shape of each snowflake depends on local climatic conditions within the precise area of the cloud where it is formed. As such, no two snowflakes are identical, with each individual pattern emerging as the crystal grows. Simple prism snowflakes are solid hexagonal prisms.