When you encounter a stone you don’t recognize, your natural instinct will be to try to identify its name right away. The hue makes you think of X, the brightness of Y, and the quick look through a loupe gives you Z among other clues. But that’s usually when the examination becomes unreliable. By following a set routine, you give yourself time to stop, to see and record what you are seeing, and to not allow yourself to become overly influenced by an initial guess.
First, get your stone ready to view. Loose stones should be wiped clean with a lint-free cloth and handled with gem tweezers or a stone holder. View the stone against a neutral background and in well-diffused white light. If your stone is mounted, take note of the areas that are inaccessible due to prongs, a bezel, or the setting. Unavailable areas need to be recorded as part of your field notes because they may preclude proper surface evaluation or instrument measurements.
Start your inspection without magnification. Note the principal color, transparency, luster, and general appearance of the cut and stone integrity. Move the stone around and look for color variation, zoning, pleochroism, unusual reflections, and different degrees of transparency within the stone. Examine the facet junctions and edges for abrasion and chipping. These preliminary observations set a foundation of knowledge upon which the 10x loupe will build.
Now, look at the surface of your stone through the loupe. Position the loupe very close to your eye and bring your stone into focus, examining one section at a time. Focus on the table, crown facets, girdle, and any visible parts of the pavilion. Look for scratches, polishing marks, coatings, small chips, rounded facet edges, and fractures reaching the surface. Some anomalies may just be reflections if they move as you move your stone, whereas some are deposits that will wipe off with a little extra cleaning.
Once you’ve finished the surface inspection, begin looking inside the stone. Turn the stone slowly in front of a directional light source, shifting the focus to various levels. Describe the form and location of the inclusions instead of simply noting that there are inclusions. Are the inclusions rounded, angular, thread-like, reflective, single, or clustered? Don’t let the fact that an inclusion is unusual lead you to believe that the stone must be natural, because inclusions can occur in synthetic stones and imitations as well.
As an exercise, examine one of your stones twice using the same procedure. During the first inspection, make all your notes before opening your book or electronic reference. Clean your stone, turn the light source to a new angle, and go through the procedure again. Now, review your two sets of notes, identifying the observations you saw in both inspections. Notes that are consistent are much more meaningful than those that are seen once.
Only after completing your visual inspection should you start comparing your findings to published information or preliminary instrument readings. Transparency, luster, inclusions, RI, fluorescence, and other properties must be evaluated together. Before declaring the name of your probable stone, ask yourself if there are unobserved areas, doubtful readings, or observations dependent on only a few angles. A systematic examination may result in several candidates or the necessity for lab analysis, but this approach is far better than jumping to conclusions with insufficient data.
