All, An alert for all. A gemstone dealer I know has just received a
parcel of the best top blue sapphires you have ever seen. At a
price that was much lower than what they should have cost.
Accompanying the stones was a certificate from a USA gemstone
laboratory that stated the stones were natural and only heated.
Suspecting something was astray, he checked them out and discovered
that the stones were diffused. Special techniques of immersion,
magnification, and a life time of sapphire knowledge were needed to
detect the treatment. He sent the stones back to their source along
with an explanation of what he had found. Diffusion is becoming
almost impossible to detect. Beware of deals too good to be true.
Gerry Galarneau
Gerry, Thanks for the warning. I was unaware that the diffusion
technology had changed. How is it that this process is getting more
difficult to detect? Is the enhancment getting deeper?
John Sholl G.G.
Littleton, Colorado
All, Normally diffused sapphires can be identified by immersing the
stones and looking for the spiderweb effect caused by repolishing.
These stones did not show any spiderweb effect under normal
observation. Two clues in the parcel alerted the dealer. First the
parcel contained multiple stones of 1-5 carats that were almost
identical in color. All high color Ceylon Blue. Second the price
was almost 1/2 of what these stones should have cost. Only very
close inspection under immersed and magnified conditions brought to
light the minor thickness variations in the polish on the facets.
Close examination showed the effect in multiple areas on each stone.
I have heard that stones can be diffused to a depth of 2mm. That is
more than enough room for a good cutter to repolish and leave very
little evidence of the process. Buyer beware.
Gerry Galarneau