Star sapphire
Cut as a cabochon, star sapphire reveals a six-rayed star that moves with the light. It is a collector’s stone, judged on the sharpness of its star as much as on its colour.
Maiwis editorial team
Where the star comes from
Some sapphires contain very fine rutile needles, aligned in three directions in the crystal. Cut as a cabochon, the stone reflects light off these needles and a six-rayed star appears. The phenomenon is called asterism. The star glides across the surface of the stone when you move it or when the light moves.
What gives a star sapphire its value
| Criterion | What we look at |
|---|---|
| Star | Six sharp, straight rays of equal intensity, reaching the edge of the stone. |
| Centring | The star must form at the top of the cabochon when the light comes from above. |
| Colour | A saturated blue ground remains the most sought after. Black, grey or pink stars have their admirers too. |
| Transparency | Translucent stones, where the star floats over a living colour, are worth more than opaque ones. |
| Proportions | A cabochon that is too thick hides weight under the stone, adding nothing to its beauty. |
Origins
Sri Lanka produces renowned blue and grey star sapphires. Burma has yielded some very fine ones. Thailand is known for its black star sapphires, with a star that is often golden.
Traps to avoid
Synthetic star sapphires have been made since the late 1940s. Their star is often too perfect, too sharp, on a very uniform ground. There are also stars created artificially by surface diffusion. Only a laboratory can settle the question, and its report must accompany any stone of value.
Star sapphire: the weight and cut you choose
The House does not hold a fixed stock. You describe what you are looking for, we search through our sources and present a short selection.
The weight
From a few tenths of a carat up to major collector pieces. Give us a range, for example 2 to 3 carats.
The cut
Oval, cushion, emerald cut, round, pear, heart, radiant or cabochon: the shape is chosen according to the jewel you will have made.
The colour
The shade, the intensity and the treatments you accept or exclude. The more precise the request, the faster the search.
As soon as a stone matches, we send you its photographs, a video, its laboratory report and its price, with no obligation. You then decide. The House supplies the exceptional stone; the jewel is made by the jeweller of your choice. Orders are taken worldwide, and stones can be viewed in person in Paris, by appointment.
Place an orderFrequently asked questions
How do you see the star of a sapphire?
Under a single light source, such as the sun or a lamp. Under diffuse lighting, the star fades.
What is a black star sapphire?
A very dark sapphire whose star often appears golden. Thailand is a known source.
What is the most famous star sapphire?
The “Star of India”, a sapphire of over 560 carats, displayed at the American Museum of Natural History in New York.
