The short answer: a colour change sapphire shows one colour in daylight and another in incandescent light, such as blue in daylight and purple in warm light, because of how the stone absorbs and transmits different wavelengths. Look at it in both kinds of light before you choose.
Colour change stones are among the most intriguing in gemmology. The effect is a property of the stone, not a trick, and it makes each piece feel alive.
How it works
Light from the sun and from a warm bulb contains different amounts of each colour. A colour change stone absorbs light in a way that makes it look different under each source. Trace elements in the crystal control this.
Typical changes
- Blue in daylight to purple in warm light.
- Greenish in daylight to pinkish or reddish in warm light.
- Grey blue to violet.
How strong is the change?
Some stones change dramatically and others only a little. A strong, clear change is more sought after. The colours on each side should both be attractive.
How to judge one
- View it in natural daylight.
- View it under a warm incandescent or candle like light.
- Compare the two colours and decide whether you love both.
On video we can show you the stone in both lights.
Why LED lighting changes things
Modern LED bulbs vary a great deal. Some are close to daylight and some are close to a warm bulb, so a colour change stone can look different from room to room. This is part of the charm, but it helps to know before you buy. If your home is lit mostly by cool white LEDs, the stone may stay on its daylight colour more often.
Colour change and colour shift
Gemmologists sometimes separate a true colour change, where the stone moves from one distinct colour to another, from a colour shift, where it moves only slightly within a family, such as from blue to a slightly more violet blue. Both can be lovely. A report may describe the effect, and we explain what it means for the stone you are considering.
Natural and lab grown
Colour change sapphires exist as natural stones and as lab grown stones. Lab grown versions can be made with a strong effect. We describe each clearly. See lab grown sapphire, ruby and emerald vs natural.
Settings
A simple solitaire lets the changing colour take centre stage, and a halo of white diamonds sets off both colours. Yellow and rose gold flatter warm light colours, and white metals suit cooler tones. Choose the metal while looking at both colours, since a metal that suits one may not suit the other as well.
Durability
Colour change sapphire is as hard and durable as other sapphires, so it suits daily wear. See our guide to cleavage and chips for how to look after it.
Related stones
Alexandrite is another famous colour change gem. It is rarer and more expensive, and we can discuss what is available when you get in touch. See alexandrite rings explained.
See best settings for sapphire and heated vs unheated sapphires, and browse diamonds for accent stones. Nothing is made until you approve the design in writing, and our standard making time is 5 to 6 weeks, which can vary with your location and how busy we are. Pieces start from £600.
Frequently asked questions
Does the colour change fade? No, it is a property of the stone.
Is it a good engagement stone? Yes, for people who like something unusual.
Can it be treated? Some stones are treated, and a report should say so.
Will it look different at home? It may, depending on your lighting, which is part of its charm.
How can I see the change before buying? We show the stone on video in daylight and in warm light.