About Sapphires
The blue sapphire is, alongside the diamond, the most universally prized gemstone in the Western tradition. A variety of the mineral corundum (aluminium oxide, Al2O3), sapphire owes its blue colour to trace amounts of iron and titanium occupying lattice sites that would otherwise be filled by aluminium. Where the trace-element balance is exceptional, the result is the gem of kings — the velvety cornflower of Kashmir, the royal blue of Burmese Mogok, or the bright sky-blue of the Sri Lankan Ratnapura district.
Origin determination is the most economically significant question in modern sapphire certification. A high-clarity, eight-carat unheated Kashmir sapphire may sell for two hundred thousand US dollars per carat at auction; the same stone identified as Madagascar will trade at a small fraction of that price. The analytical task — reading the trace-element signature, inclusion suite, and absorption spectrum to a definitive country-of-origin conclusion — is the central work of an origin-capable laboratory. AGL's Sri Lanka, Antwerp, and Shanghai laboratories all deploy LIBS (Laser-Induced Breakdown Spectroscopy) and ED-XRF to record trace iron, titanium, vanadium, gallium, and chromium levels, FTIR spectroscopy to detect heat treatment and beryllium diffusion, and UV-VIS-NIR absorption spectroscopy to record colour-causing centres. These instrumental records are then compared against our reference collection of confirmed-origin material drawn directly from the Ratnapura, Elahera, Mogok, Mong-Hsu, and Madagascar deposits.
Heat treatment is the most common enhancement applied to sapphire. Standard low-temperature heating (around 1,200°C in air) improves colour saturation by reducing iron oxidation states and dissolves silk inclusions; high-temperature heating with the addition of beryllium produces an entirely different colour result and is classified separately as a chemical-diffusion treatment. Every AGL sapphire report states the heat-treatment status plainly: “No indications of heat treatment,” “Indications of heating,” or “Indications of lattice diffusion.” We never describe a beryllium-diffused stone as merely “heated.”
Beyond blue, the corundum family includes the entire colour wheel: yellow sapphires (Sri Lanka dominant), pink sapphires (Madagascar, Sri Lanka), padparadschas (covered separately), purple, green, and white sapphires, and the rare colour-change varieties that shift from blue-violet under fluorescent light to red-purple under incandescent. Star sapphires — cabochon-cut stones displaying a six-rayed asterism caused by oriented rutile silk inclusions — are a Sri Lankan speciality, and our Beruwala laboratory maintains an extensive reference collection of star material from the Ratnapura and Elahera districts.
For Ceylon sapphire buyers, the AGL certificate provides the three statements that determine value: the species and variety (natural sapphire of the corundum species), the heat-treatment status (preferably none, though heat is universally accepted), and the origin (Ceylon being among the most prized, alongside Kashmir and Burma). Each of these statements is supported by recorded analytical data, and each is verifiable online at any time through our secure portal.
How AGL certifies Sapphires
Every sapphires submitted to an AGL laboratory is examined by at least two senior gemologists and analysed using our standard instrumental package: refractive-index and specific-gravity measurement, microscopic examination under dark-field and fibre-optic illumination, UV-VIS-NIR absorption spectroscopy, FTIR spectroscopy for treatment detection, and LIBS or ED-XRF for trace-element analysis where origin is in question. Every conclusion on the certificate — species, variety, treatment, origin — is supported by recorded analytical data, and every certificate is recorded in our secure verification database for online authentication at any time.
For full service descriptions and turnaround times, see our Services page, or contact your nearest AGL laboratory for a written quotation.
