In one paragraphCrystal colour is sometimes natural and sometimes the result of heat, irradiation, dye or coating. None of these is inherently dishonest — heat treatment is stable and often just continues what nature does — but disclosure is everything. This chart shows, stone by stone, which treatments are common, how to spot them, and what counts as a warning sign. The rule of thumb: vivid, perfectly even, suspiciously cheap colour is usually dye; subtle zoning usually means natural.
Two amethyst bracelets at very different prices can both be “real” amethyst — and a third, brighter one might be dyed quartz entirely. The difference that matters isn’t whether a stone was touched, but whether the seller tells you. BE. treats treatment as a recorded fact, not a secret, and this guide is the reference behind that policy: what gets done to which stones, and how to read it yourself.
Treatment chart by stone
| Stone | Common treatment | How to tell |
|---|---|---|
| Citrine | Often heated amethyst | Very even orange; reddish tint hints at heating. |
| Prasiolite (“green amethyst”) | Heated amethyst | Always pale leek-green; vivid green = dye. |
| Smoky Quartz | Sometimes irradiated | Perfectly even jet black hints at treatment. |
| Amethyst | Usually untreated; some dyed imitations | Subtle zoning natural; dye pools in cracks. |
| “Strawberry / cherry quartz” | Frequently dyed or glass | Flawless even colour, bubbles = manufactured. |
| Clear Quartz | Typically untreated | Colourless; coatings add unnatural rainbow sheen. |
| Rutilated Quartz | Typically untreated | Natural rutile needles; no colour added. |
| Hematoid Quartz | Typically untreated | Natural iron-oxide veils and phantoms. |
| Rose Quartz | Usually untreated | Soft cloudy pink; vivid pink suspect. |
| Aquamarine | Often heated (greenish to blue) | Common, stable, should be disclosed. |
| Moonstone, Garnet, Obsidian, Kyanite | Generally untreated | Effects (glow, colour) are structural/natural. |
The four treatments, explained
- Heat. Continues a natural colour change — amethyst to citrine or prasiolite, greenish beryl to blue aquamarine. Stable and permanent; should be disclosed.
- Irradiation. Creates or deepens colour centres (smoky quartz). The colour is from rearranged electrons; the stone is not radioactive afterward when properly sourced.
- Dye. Adds pigment from outside. The least desirable here — betrayed by over-even colour and dye in cracks. Common in cheap “bright” quartz.
- Coating. A surface film (e.g. “aura” quartz) producing metallic rainbow sheen. Surface-only and can wear; always a treatment, never natural.
Spotting treatment yourself
- Look for zoning. Subtle, uneven colour bands usually mean natural; flat uniform colour can mean dye or heavy treatment.
- Inspect cracks and holes. Pigment pooled there is a dye tell.
- Be sceptical of vivid + cheap. Intense colour at a low price rarely comes from nature.
- Check sheen. Metallic rainbow surfaces indicate coating.
- Ask for disclosure. A straight answer about heat, irradiation or dye is the mark of an honest seller.
How BE. handles treatment
BE. records any treatment on the Stone Origin Card that ships with each strand, alongside the mineral, hardness and source — the same transparency it applies under the Crystal 4T framework (Transparency, Tone, Texture, Treasure). Where a colour is natural, the card says so; where it results from heat, it says that too. The point isn’t to avoid all treatment — it’s to never hide it.
Frequently asked questions
Q1.Are most crystals treated?
It varies. Citrine is often heated amethyst, prasiolite is heated amethyst, and bright dyed quartz is common cheaply — but many quartz stones like clear, rutilated and hematoid quartz are typically untreated. Disclosure separates honest sellers.
Q2.Is heat treatment bad?
Not inherently. It is stable, permanent, and continues a change that can happen in nature. The issue is disclosure, not the treatment itself.
Q3.How can I tell if a crystal is dyed?
Dye shows as unnaturally vivid, perfectly even colour with pigment in cracks and around drill holes. Natural stones show subtle zoning. Cheap, saturated, uniform colour is the main warning sign.
Q4.Is irradiated smoky quartz safe?
Yes. The colour is from rearranged electrons, not retained radioactivity. Properly sourced smoky quartz carries no measurable residual radiation.
Q5.What does untreated mean?
The colour and clarity are as formed in nature — no heat, irradiation, dye or coating. Many quartz stones are attractive untreated, which is why honest untreated material is valued.
Q6.Why should treatment be disclosed?
It affects value, rarity and sometimes care, so disclosure lets you choose and compare fairly. A seller who records treatment is informing you, not hiding it.
References
- Gemstone Treatments — GIA
- Gemstone treatment — Wikipedia
- Mineral data — Mindat.org
- Nassau, K. (1984). Gemstone Enhancement. Butterworths.
- Rossman, G. R. (1994). Colored Varieties of the Silica Minerals, Reviews in Mineralogy 29.
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