How to identify a sapphire?

A natural sapphire can be mistaken for two families of lookalikes. First, treated sapphires : stones whose appearance has been artificially altered — through beryllium or titanium diffusion, lead-glass filling — to appear more beautiful than they are, undetectable to the naked eye. Then, other stones : a blue sapphire can resemble a blue spinel or a tanzanite, although their compositions are very different. And the confusion applies to every colour: distinguishing a pink sapphire from a pink spinel, with similar clarity and brilliance, is difficult even for a trained eye.

The stakes are not trivial: sapphire is one of the most popular gemstones, particularly for engagement rings — and it is precisely among the most sought-after stones that imitations proliferate.

Let us be direct: at-home methods for identifying a sapphire are unreliable. They may rule out crude imitations, but can never authenticate a stone. Here they are, for what they are worth:

• The fog test — breathe on the stone: on a genuine sapphire, the fog evaporates almost instantly; if it lingers, be wary (it may be glass). Useful against low-grade fakes, ineffective against a treated sapphire.
• The lamp test — in the dark, under a small lamp, some fake stones reflect a “suspicious” light that is too uniform. Highly unreliable.
• The search for bubbles — genuine sapphires do not have air bubbles ; glass imitations and lead-glass-filled stones may contain them. But they are not always visible to the naked eye…
• Imperfections — a genuine sapphire often has slight natural inclusions, whereas a heavily treated stone may appear strangely flawless for its price. An interesting clue, but beware: very beautiful natural sapphires may also have no visible imperfections.

The most reliable way to identify a sapphire is to have it analysed by an independent laboratory — we explain who to turn to — and to request its report (SSEF, GRS, GIA, Gübelin, etc.). The report identifies the mineral species, probable geographical origin and any treatments — including heat treatment, which must be distinguished from treatments that alter the stone: our guide to heated sapphire details this essential distinction.

This is our rule, without exception: every sapphire sold by Bonnot Paris comes with its independent laboratory certificate — you have nothing to verify; proof is provided as standard. To go further: our Angers showroom, and our guides to recognising a gemstone and recognising a ruby.

Authentic does not mean exceptional: quality must also be assessed. As with diamonds, it is measured through the 4Cs :

A good-quality sapphire may be a heated sapphire — heat treatment is an accepted traditional process, declared on the certificate — but not a “treated” sapphire in the sense of processes that alter the stone (diffusion, filling), which we refuse.

• Not all dark blue sapphires are the most expensive or the most sought-after. However, sapphires that are too pale are not sought after in jewellery.
• The price of a blue sapphire varies according to quality (the 4Cs) and weight. Most of the time, a small blue sapphire of excellent quality costs more than a larger one of lower quality.
• The best way to avoid being scammed: buy a sapphire with a laboratory certificate, from a trusted seller who can provide you with all the information — origin, treatment, characteristics.

And to see authenticated stones set in jewellery, browse our blue sapphire engagement rings — or the entire sapphire collection : each creation specifies the origin, treatment and certificate of its stone.