Sri Lankan Yellow Sapphire

Buying this stone

Where it came from, what its weight band is for, and what to check before any money changes hands.

The deposit

Ratnapura, whose name translates as city of gems, is the traditional district for Ceylon yellow sapphire and the classic source for Pukhraj. The material there runs from a pale straw through lemon to a full golden yellow, and the metamorphic, low-iron chemistry is what keeps it bright rather than pushing it towards brown. Sri Lanka is also the source of most of the world’s near-colourless and pale corundum, which matters here for an unhelpful reason: pale Ceylon rough is the standard feedstock for the heat and diffusion treatments that produce cheap yellow sapphire.

This stone

At 8.03 carats this is a large Pukhraj, and Pukhraj is the Navratna stone most often prescribed by weight, which makes this band commercially distinct from every other sapphire in the catalogue. Astrological practice specifies weight in ratti, and the ratti to carat conversion is not standardised: two conventions are in common use and they differ by close to a third. Confirm which one your astrologer intends before buying to a number, because the difference between them at this size is well over two carats of stone and a great deal of money.

Treatment

Unheated and untreated, which for yellow sapphire is a substantially rarer position than for blue. Most commercial yellow corundum on the market started as pale Ceylon rough and was heated, and a proportion of the strong orange-yellow material in circulation is beryllium diffused, which is a different treatment requiring its own disclosure and worth a fraction of natural colour. The word treated on its own does not separate these, so ask which. This stone was never in a furnace and its colour is the colour it grew with.

The report

A IIGJ report is held for this 8.03 cts yellow sapphire and is handed over with it. Verify the number with the laboratory rather than only with us, and check its weight against the stone before money moves.

Before you pay

• Look through the table for colour pooling in bands or concentrating at the girdle, which is what diffused colour does.
• Check that the weight on any report matches the stone in front of you before money moves.
• Settle the ratti convention in writing with whoever prescribed the weight, before you commit to a stone at a specific number.

Read next

Pukhraj, the yellow sapphire covers the material itself and what gets sold in its place. How to buy a coloured stone covers pricing, treatment and reports.

Written by Kamal Kishore Agarwal, founder and gemmologist, Gem-A qualified, buying in Johari Bazaar since 2008.