Carlsbad, Calif.—The Gemological Institute of America discovered two lab-grown stones and a simulant in a gaggle submitted to its Carlsbad laboratory as pure sapphires.

In keeping with a lab notice written by Najmeh Anjomani in GIA’s Summer season 2022 Gems & Gemology problem, its Carlsbad lab just lately obtained 4 tough blue stones submitted as pure sapphires for identification and origin studies.

The most important weighed 48.63 carats. It was partially normal, GIA stated, with proof of polish traces on its floor.

Examination underneath a microscope revealed gasoline bubbles, distinct circulation marks, and conchoidal fractures, whereas the polariscope revealed weak snake sample bands. Its hydrostatic particular gravity (SG) was 2.48.

All these observations collectively urged a glass imitation, GIA stated, which was confirmed by evaluating the infrared spectrum with that of artificial glass.

Two of the opposite submitted blue stones, weighing 9.17 carats and 6.21 carats, had been “extra convincing imitations of pure sapphire,” GIA stated.

There was a resin coating their surfaces that resembled a matrix generally seen on pure tough corundum. GIA stated the resin began to soften when touched with a scorching level. 

And although their tough surfaces made it troublesome to see contained in the stones, GIA was capable of observe a number of gasoline bubbles by way of a clear space. 

It additionally carried out Raman spectroscopy, the outcomes of which matched corundum, and immersed the stones in water, revealing curved blue banding. 

GIA stated laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) revealed hint components matching artificial corundum. SG values had been discovered to be 3.76 and three.59, respectively, each of that are under the SG of corundum (3.9-4.05) and are a results of the decrease SG of the floor resin. 

The lab issued studies for each figuring out them as lab-grown sapphires. 

Lastly, the fourth tough blue stone submitted weighed 8.46 carats. 

It had a “frosted” pure floor that made it laborious to see inside, however GIA stated it was capable of observe some natural-looking fingerprints and robust, straight “inky” blue banding. 

The lab immersed the stone in methylene iodide to verify the colour zoning it noticed was straight, a sign of a pure origin. 

The Raman spectrum matched that of corundum, additional confirmed by SG of three.96. 

GIA put the stone underneath shortwave UV and noticed a medium chalky blue fluorescence. 

LA-ICP-MS revealed a pure chemistry, together with iron and hint components corresponding to gallium, vanadium, magnesium, chromium, and titanium.

Given its look, shade zoning, and chemistry, the stone was recognized as a pure sapphire, with its report noting it had been heated and was of Madagascar origin. 

Anjomani stated within the lab notice that the 4 submitted stones offered an “attention-grabbing research of how synthetics and simulants might be blended with their pure counterparts to misrepresent a parcel.”

The writer famous, nonetheless, that “cautious examination and customary gemological testing are normally sufficient to determine them accurately.”