The short answer: most sapphires are heated to improve colour and clarity, and that is a widely accepted practice as long as it is disclosed, while unheated stones are rarer and usually priced higher. Choose based on the look you love, the report and your budget.
Heat treatment is one of the most common things to learn about when buying a sapphire. It is not a flaw, but you should know whether a stone has had it.
What heating does
Heating stones at high temperature can deepen or lighten colour, reduce unwanted tones and improve clarity. It is a stable treatment, and the colour does not normally fade in everyday wear.
Unheated sapphires
Unheated stones have not had this treatment. They are less common, and fine unheated stones can be particularly sought after. They may have natural colour that is more modest, or a more natural clarity.
Comparison
| Heated | Unheated | |
|---|---|---|
| Availability | Common | Rarer |
| Colour | Often improved | Natural, varies |
| Price | Generally lower | Generally higher |
| Disclosure | Should be stated | Should be stated on a report |
How a laboratory tells
Heating leaves clues inside a stone. Tiny crystals inside a sapphire can melt or change shape when heated, and fine needles known as silk can break up or disappear. A gemmological laboratory looks for these signs under magnification and with specialist equipment. Signs can be subtle, which is why an independent report from an experienced laboratory matters for a stone sold as unheated.
Other treatments
Some sapphires have had other treatments, such as diffusion or filling, which are less stable or less accepted. A report should state them, and we advise caution with any stone that has had more than simple heating.
How to check
- Ask for an independent report.
- Read the treatment line carefully.
- Ask us to explain anything unclear.
Which to choose
- If you want strong colour for the budget, a heated stone often gives this.
- If you value natural, untreated stones, an unheated stone may suit you.
- If durability matters, both are durable.
Heated does not mean lower quality
Many of the finest sapphires in jewellery have been heated, and the treatment is part of how most blue sapphires reach the market. The key is honesty: a heated stone sold as heated is fair, and the lower price reflects its availability. A price that looks too good to be true for an unheated stone deserves a question.
Colours beyond blue
Heating is used across the sapphire colour range, including pink, yellow and orange stones. Rare pinkish orange padparadscha sapphires are often heated too, and unheated examples are especially scarce. The same rule applies to every colour: ask what the report says. See padparadscha sapphires.
Lab grown sapphires
Lab grown sapphires are made in a laboratory and have the same chemistry as natural ones. They are not treated in the same way, and we label them clearly. If you want strong colour and clarity at a lower price, they are worth considering. See our guide to lab grown sapphire, ruby and emerald vs natural.
Caring for it
Heat treated sapphires wear well, and you can clean them with warm soapy water. We advise on care for each stone.
See sapphire origins explained and best settings for sapphire, 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
Is a heated sapphire fake? No, it is a natural sapphire that has been treated.
Will the colour fade? Normally not in everyday wear.
Should I choose unheated? Not necessarily, it depends on what you value.
Does heating affect durability? Not in a way that matters for normal wear.
Can I order a sapphire ring from overseas? Yes, by video consultation, with insured, tracked FedEx delivery.