Värviring

Could you specify the intended meaning and field of värviring? The term is not universally standardized and can refer to different concepts in fields such as medicine/dermatology, textiles/dyeing, or optics. Also, would you prefer the article in Swedish or English, and who is the intended audience (general readers, specialists, or students)? Once I have the context, I can write a concise, neutral wiki-style article under 300 words.