katseen

Katseen is a term that may refer to two distinct phenomena commonly described in English as “cat’s eyes.” In some contexts, it appears in discussions of gemstones and in road safety, where the term is used informally to denote the same concept in different languages.

In gemology, the cat’s-eye effect, or chatoyancy, appears as a narrow, bright band of light that moves across a cabochon when the stone is rotated under a light source. The phenomenon is most famously associated with chrysoberyl, known as cat’s eye chrysoberyl, but it can also occur in other minerals such as quartz and tourmaline. The band results from aligned, fine inclusions or fibrous structures within the mineral that reflect light in a single, luminous line. Jewelry cut to maximize the chatoyancy often uses a domed shape to enhance the effect.

In road safety, cat’s eyes refer to retroreflective roadway markers that improve nighttime visibility and lane definition. The concept is widely credited to Percy Shaw, who demonstrated the idea in the United Kingdom in the 1930s. Traditional cat’s eyes consist of reflective elements embedded in the road surface, sometimes arranged in pairs to mark lane edges and central lines. Modern variants may use advanced materials and colors to indicate different traffic cues, while routine maintenance ensures visibility through wear and weathering.

The spelling and usage of katseen vary by language and context; Dutch terminology for related concepts more commonly uses terms such as kattenoog or kattenogen. See also: cat’s eye, chatoyancy, road markings.