Blue Sapphire

Blue sapphire is corundum coloured by an interaction between iron and titanium, specifically an intervalence charge transfer between adjacent Fe and Ti ions, which absorbs strongly in the yellow-red and leaves blue. Very small quantities suffice, on the order of hundredths of a percent, which is why the same mineral that is colourless as pure aluminium oxide can be intensely blue.

Sapphire occurs in every colour; padparadscha, a pinkish orange, is the most valued of the fancy colours and the name is Sinhalese, from the lotus. Star sapphires show asterism, a six-rayed star produced by reflection from oriented needles of rutile within the stone, and the same inclusions in fine dispersion produce the velvety quality of the best Kashmir material.

The important geographical fact is that Sri Lanka (Serendib, Taprobane, Ceylon), has been the classical source for two thousand years and remains a major one. Kashmir sapphires from a deposit worked briefly from the 1880s are the most prized and effectively exhausted. Burma, Madagascar and Montana are other sources.

Heat treatment to improve colour and clarity is near-universal and long-established; beryllium diffusion treatment is a more recent and more contentious process.

In medieval Europe sapphire was the ecclesiastical stone, worn in bishops' rings and read as celestial truth and chastity, and the lapidaries are full of it. That literature requires the caution set out elsewhere in this collection: earlier sources using the word mean lapis lazuli, and the transfer of the name to blue corundum happens gradually through the medieval period, so a thirteenth-century text may mean either.

In jyotisha blue sapphire is neelam, the gem of Shani, Saturn, and it occupies a distinctive place in the navaratna: it is held to be the fastest-acting of the nine gems and the most dangerous.

The tradition around it is unusually specific and is worth reporting accurately, because it is the clearest example of a gem prescription that comes with its own contraindication. Practitioners hold that neelam produces its effect immediately, within days or even hours, and that the effect is unambiguously good or unambiguously bad according to whether Saturn is well placed for the wearer. The customary procedure is a trial period, the stone worn briefly and removed if misfortune follows. It is not to be worn casually, and reputable practitioners will refuse to prescribe it without a chart.

That structure, a powerful remedy with a built-in test, is common to serious divinatory and remedial traditions and is worth distinguishing from the generic beneficence of most modern crystal literature, where no stone ever does harm and none is ever unsuitable. Whatever one thinks of the underlying claim, the jyotisha material is making a falsifiable-shaped assertion and the popular Western material generally is not.

The Western tradition assigns sapphire quite differently, most often to Jupiter or to the Sun by way of its heavenly and royal associations, and Agrippa pairs sapphire with the fixed star Capella in the Behenian scheme. These are not variants of one tradition; they are separate systems that happen to use the same stone, and reconciling them is not possible and should not be attempted.

Sapphire is the September birthstone on the 1912 list.