In our final video for our January turquoise grading month Mike looks at some very high grade dark web turquoise from three different mines and grades them using the Turquoise Grading Rules based upon the Robert's Ryan rules for turquoise grading to determine an R2 alpha/numeric grade. Try grading these yourself to see how your grades compare understanding that an actual grade may not be assigned from a photo.
Hi Mike, in the video or at least on my screen (which has pretty good color), the color of all of these stones looks almost identical. I wonder if there's any value in having some kind of pantone index color or other reference color by which to help judge turquoise color. I know it's a little subjective, and some of the blues seem to have added depth, maybe due to silica content (the very best Bisbee blue does this, at least for some of my gem grade stones).
Any thoughts?