An estimation of the value of a diamond article is called what?

The term that best describes an estimation of the value of a diamond article is "an appraisal." An appraisal is a professional assessment of the diamond's worth, usually conducted by a qualified gemologist or appraiser. This evaluation takes into account various factors, including the diamond's size, quality, cut, color, and clarity, along with market trends to determine its financial value.

While certifications and grading also relate to diamonds, they serve different purposes. A certification provides verification of a diamond's features and authenticity, often issued by a gemological laboratory. Grading involves assessing the quality of a diamond based on established criteria but does not necessarily assign a monetary value. A valuation report, on the other hand, is similar to an appraisal but may be more comprehensive and include detailed documentation and descriptions. However, "an appraisal" specifically focuses on estimating a diamond's value, making it the most accurate term in this context.