Only three stones officially bear the name of precious stones alongside the diamond: sapphire, ruby and emerald. All the others, however beautiful, are fine stones. For these three stones, value is not read as it is for a diamond: it is the intensity and purity of the colour, the geographical origin and whether or not the stone has been treated that make the price difference, sometimes by a factor of ten for a comparable apparent colour.
| Stone | Most sought-after origins | Key point |
|---|---|---|
| Sapphire | Kashmir, Burma, Ceylon | Velvety blue, saturation without excessive darkness |
| Ruby | Burma, Mozambique | The so-called pigeon's blood red, no heating |
| Emerald | Colombia, Zambia | Deep green, nature of the oiling |
The vast majority of coloured stones on the market have been treated, most often by heating for sapphire and ruby, and by oiling for emerald, whose natural inclusions, the jardin, are inherent to the stone. These practices are accepted when they are disclosed. A certified unheated stone trades well above a treated stone of equivalent colour. We state what the gemmological report establishes, without extrapolating.
Because some historic mines, now exhausted or closed, produced colours that are not found anywhere else. Only a laboratory can give an opinion on an origin.
No, it is the norm for this stone. What matters is the nature and extent of the oiling, stated on the report.
Important stones are sold with their laboratory report when one exists. We can also have a stone analysed on request.
