Prior Documentation? Why do I ask?

1. If you have a grading report from an independent lab such as GIA, AGS, EGL this means that your diamond or gemstone was graded outside of the mounting, in a controlled environment with the results stating the actual characteristics (such as weight). This information should be documented within the report because, grading of a diamond or gemstone in the mounting is limited by the mounting, e.g., yellow color of the gold, prongs hiding an inclusion etc.
2. Match the item to the previous description to make sure they are one in the same.
3. If my grading differs from the previous findings, we can discuss it immediately, face to face, and not after the report was issued.

Grading is a subjective scientific procedure. Grades on the same diamond/gemstone may vary from one professional, trained grader to another, depending upon conditions of lighting, time allowed for grading, quality and accuracy of master (comparison) diamonds, and color and hue discrimination abilities of the gemologist. 

Some insurance providers utilize an annual automatic inflation adjustment to values which may or may not be a fair representation of an items actual current value.