Canary Diamond vs. Yellow Sapphire: Visual Differences & Key Distinctions

Question
Hi Thomas,
I was wondering how to tell the difference between canary diamonds and yellow sapphires. I understand there is a differnce in the hardness of the stones. I am specifically wondering about differences that are can be seen by the naked eye.
Thanks,
Mel

Answer
Mel, I am not an expert on this but am an expert in putting either into a fine piece of jewelry art. : ) However, I will mention some basic differences in sapphire and diamond which with comparison you should be able to see easily, or certainly see with the magnification of a jeweler's loupe.

DISPERSION


This is the ability of the crystalline substance to break up light into the spectrum. The fire of a stone may be a reference to the reflected light from the polished surfaces or more accurately the glimpses of other color seen in the reflections.  Diamond will have higher dispersion than sapphire and this is true in the yellow ones.

Web Article on Dispersion and More:
http://www.minelinks.com/alluvial/diamonds5.html

Sapphire will show much less if any noticed break up of light into the spectrum of colors.  The following chart shows dispersion values for various gemstones.  You will note that sapphire is much lower than diamond:

http://www.gemselect.com/gem-info/dispersion-chart.php


SHARPNESS OF POLISHED EDGES

This will require a magnification similar to a jewelers loupe lens. Hold the lens to the eye and bring the stone to the lens with one finger out to support the stone and magnifier and reduce shake.  

Look at the facets (the cut and polished faces) of the gemstone. You will see in most all cases a superior polish on diamond. You do need to look at both to see the difference then it is quite clear.  Now, look at the junctions of the facets; these are the edges where one flat face meets another. On a diamond the meet will be a sharp line with no rounding of the edge where the faces meet.  On most other gems including sapphire, you will see some rounding of the edge. Also, the meeting of the faces will generally not be so clean and uniform on other gemstones as demonstrated in diamond cutting.  Only a quite well cut sapphire will show fine joining and fine uniformity of the facets.

Mel, other tests are out there but require more than the loupe or naked eye.  I do hope this helps.

God Bless and Peace.  Thomas.