Sapphires Illustrate the Wonder of Gems and the Limits of Perception

July 14th, 2010 by James L. Sweaney, CGA, FGA. GG
5 ct. Ceylon sapphires

5 ct. Ceylon sapphires

These two sapphires are both from the island of Sri Lanka, both are heat enhanced, both are from the same vendor, both weigh about the same.

5 ct. Ceylon sapphires, v2

5 ct. Ceylon sapphires, v2

Here's another photograph, same stones, same photographer (myself), same camera, same photo stage, similar macro lens, slightly different lighting. Can you guess which one costs more?

These beautiful  Ceylon sapphires illustrate the problems we in the gem trade have when trying to communicate the subtle nuances of color and appearance of gems.

Photographs don't always help because as you can see from the two photos, very subtle differences in technique or equipment can create big differences in appearance.

The stone on the left weighs 5.04 cts, the other weighs 5.68 cts, so if the price per carat were the same, the 5.68 ct. stone would cost 12.7% more.

Actually, the 5.68 on the right, costs 60% more than the 5.04.

Having looked at these two stones personally, under various conditions, I don't have a good explanation for the big difference in value. Using our sophisticated grading system as shown in Gemology 101, these two stones test the limits of our system– the color of both would be described as Extra Fine,  strong medium dark blue, graded 8.5 to 9. The main grading difference I see would be for cut– the stone on the right showing a bit more brilliance, and perhaps a more pleasing shape.

Since the two stones are from the same vendor, the big difference could be explained by old stock vs. new stock, the vendor's grading style, etc., or it could just be that one stone is a bargain or the other is expensive, whatever the reason. The gem trade doesn't always make sense!

This comparison shows why it's important to compare gemstones side by side whenever possible and why it's important to work with experts who can show you the quality factors that matter. Then you can make a informed choice.

At Mardon, as members of the American Gem Trade Association and the American Gem Society, we are dedicated to maintaining and upgrading our skills and to consumer protection thru the education and information we provide our clients.

Here on our website, you can study our free gem grading course, Gemology 101, view full grading reports on our Gallery of Gems, and of course follow our Blog. We hope you'll enjoy the wonder of gems like we do!

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