Can I tell real alexandrite from a photo?

Photos can help but are not definitive. Colour change may appear differently due to camera white balance and lighting. Use photos taken under both daylight and warm indoor light, and treat them as part of initial evidence rather than proof.

Are there common simulants or imitations I should watch for?

Yes. Colour‑change spinel, glass, synthetic corundum and assembled doublets are among materials used to imitate alexandrite’s colour change. Many simulants will lack the internal growth features of natural chrysoberyl or will show different reactions under filters and magnification, so use multiple non‑destructive checks or seek lab testing.

Will a Chelsea filter or dichroscope give a final answer?

No single tool gives a final answer. A Chelsea filter and a dichroscope can provide useful clues but have limitations and false positives. Combine several non‑destructive observations and get a laboratory report for definitive identification.

Is lab‑grown alexandrite detectable?

Lab‑grown alexandrite exists and can be separated from natural material by trained gemologists using microscopy and spectroscopy. If you need certainty about origin, ask for a laboratory report that states whether a stone is natural or synthetic.

How to tell if an alexandrite is real

Alexandrite is valued for a dramatic colour change and specific physical properties. The name refers to the colour-change phenomenon: it is the colour-change variety of chrysoberyl. This page lists safe, practical checks you can do yourself and explains when to seek lab testing.

Quick facts

Hardness: 8.5 on the Mohs scale
Species: the colour-change variety of chrysoberyl

Quick visual checks you can do at home

Look at the stone under two light sources: a strong daylight-equivalent (or outdoor daylight) and a warm incandescent or tungsten lamp. A real alexandrite often shows a clear shift in dominant colour between those lights. Check the stone for any obvious glue, filler, doublets or assembled layers around the girdle or pavilion. Rotate the stone slowly and note whether the colour change is consistent across the gem rather than only on one side.

Hardness and handling

Alexandrite has a durable surface and will resist many common scratches: 8.5 on the Mohs scale. Do not perform scratch tests on jewellery you care about; scratching or abrading a mounted or loose gem can damage it and reduce its value. Instead use non‑destructive methods first and keep the stone mounted while you inspect it unless a qualified gemologist requests removal for testing.

Tools and non‑destructive tests

Use a 10x loupe or a low‑power microscope to inspect internal features. Natural stones typically show growth zoning and natural inclusions; lab-grown material can appear overly clean or show curved growth lines. A dichroscope helps reveal pleochroism; alexandrite may show different hues when viewed at different angles. A Chelsea filter can give a quick indication (red or strong pink/green response for some alexandrites) but it is not definitive. UV lamps and a simple light meter can add information but are not conclusive on their own.

Check the setting and documentation

Examine the jewellery for hallmarks, stamps and metal fineness marks such as karat or sterling stamps and assay marks. A secure, well‑finished setting in gold, platinum or palladium and a clear metal hallmark increase the likelihood the stone was intended to be genuine, but settings are not proof. Keep any paperwork, receipts, or seller statements; provenance and documented appraisals are useful when seeking formal verification.

When to get professional testing

If the stone passes home checks but you still need certainty, request testing from a qualified gemological laboratory. Labs use refractive index, specific gravity, advanced microscopy, and spectroscopy to separate natural alexandrite, lab‑grown alexandrite, colour‑change simulants and assembled stones. If a seller cannot provide a reliable lab report, ask for one before you buy. For high‑value pieces or inheritance items, a lab report gives the best evidence.

If you are still unsure

Avoid harsh or destructive tests and do not rely on a single quick trick. If you want a simple first step, record photos of the stone under daylight and under warm indoor light and compare them. For a trusted second opinion, take the piece to a local jeweller or gemologist who can run non‑destructive tests. If you prefer a digital aid for preliminary identification, try Jewelry Identifier.

Common questions

Can I tell real alexandrite from a photo?: Photos can help but are not definitive. Colour change may appear differently due to camera white balance and lighting. Use photos taken under both daylight and warm indoor light, and treat them as part of initial evidence rather than proof.
Are there common simulants or imitations I should watch for?: Yes. Colour‑change spinel, glass, synthetic corundum and assembled doublets are among materials used to imitate alexandrite’s colour change. Many simulants will lack the internal growth features of natural chrysoberyl or will show different reactions under filters and magnification, so use multiple non‑destructive checks or seek lab testing.
Will a Chelsea filter or dichroscope give a final answer?: No single tool gives a final answer. A Chelsea filter and a dichroscope can provide useful clues but have limitations and false positives. Combine several non‑destructive observations and get a laboratory report for definitive identification.
Is lab‑grown alexandrite detectable?: Lab‑grown alexandrite exists and can be separated from natural material by trained gemologists using microscopy and spectroscopy. If you need certainty about origin, ask for a laboratory report that states whether a stone is natural or synthetic.