Amethyst (or smoky quartz) roasted at roughly 400–550 °C, which converts the iron colour centres from violet to orange-brown. Stable and permanent; not a fake mineral, but a treated one, and it should be disclosed. It is not sold as treated in most shops. White chalky base plus sharp orange tips equals heated amethyst, every time. Confirm it is quartz first with a glass scratch, then read the colour boundary. Treatment is permanent and not detectable by any consumer test other than colour distribution. Amethyst (or smoky quartz) roasted at roughly 400–550 °C, which converts the iron colour centres from violet to orange-brown. Stable and permanent; not a fake mineral, but a treated one, and it should be disclosed. It is not sold as treated in most shops. A photograph gets you most of the way; the physical test settles it.
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Option two
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Pick the name on the label and we will give you the physical test for that stone, and the imitation it is most often swapped for.
Your stone
You said Citrine (Heat-Treated Amethyst).
Citrine (Heat-Treated Amethyst) is commonly faked, treated or sold under the wrong name, so the visual match is where the checking starts, not where it ends. Run the test below.
The test that settles it
White chalky base plus sharp orange tips equals heated amethyst, every time. Confirm it is quartz first with a glass scratch, then read the colour boundary. Treatment is permanent and not detectable by any consumer test other than colour distribution.
Sold under the wrong name
Amethyst (or smoky quartz) roasted at roughly 400–550 °C, which converts the iron colour centres from violet to orange-brown. Stable and permanent; not a fake mineral, but a treated one, and it should be disclosed. It is not sold as treated in most shops.
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A photograph cannot measure hardness, streak or specific gravity. We tell you what the visual signs suggest and give you the test to be certain yourself.
Natural citrine is genuinely uncommon. The overwhelming majority of what is sold under the name is amethyst, sometimes smoky quartz, roasted at roughly 400 to 550 degrees Celsius until the iron colour centres flip from violet to orange-brown. The result is still quartz, the change is permanent and stable, and it is not a fake mineral. It is a treated one, and it should be disclosed. In most shops it is not.
That is the whole question on this page: not is it quartz, but was it heated and were you told.
The white base and the hard colour line
Heated amethyst has a signature nothing else copies. Look at a cluster or a geode section from the side: a chalky, opaque, almost bleached white base that changes abruptly into saturated burnt orange at the crystal tips. Not a gradient, a line. The heat drives the colour to the terminations and leaves the body milky.
Natural citrine does the opposite. Its colour is a pale, even, slightly smoky yellow to warm honey, distributed through the crystal rather than concentrated at the point, and its base is glassy rather than chalky. If it is deep reddish-orange, it was almost certainly in an oven. Nature makes very little quartz that colour.
Shape, crazing and the geode giveaway
Heated Brazilian and Uruguayan geodes come to market as short, stubby, uniform points all facing inward, every one of them the same burnt orange, with a bleached zone underneath and a grey agate rind outside. That is an amethyst geode's architecture, because that is what it was. Natural citrine rarely occurs as a wall of identical stubby points like this.
Under a loupe, thermally shocked material sometimes shows fine surface crazing, a network of shallow cracks from the temperature ramp. That is evidence of heating. Its absence proves nothing, since careful treatment leaves no crazing at all.
Confirm it is quartz first
Before reading the colour, make sure you are holding quartz. Citrine is SiO2 at hardness 7: it scratches window glass and a steel blade will not mark it. Calcite, which turns up as dyed orange tumbles, is hardness 3 and a copper coin will scratch it. Amber is hardness 2 to 2.5, far lighter in the hand, and warm to the touch. Glass is around 5.5, carries bubbles and a mould seam, and often has a suspiciously perfect even colour.
The honest limit: no consumer test distinguishes heated citrine from natural citrine except colour distribution. There is no scratch, streak or torch test for it. Laboratories use infrared and trace-element analysis. What you can do is read the base, the colour boundary and the price.
Ametrine, smoky and the other near-misses
Ametrine is real and honest: a single Bolivian quartz crystal with a natural purple half and a natural yellow half, divided by a sharp straight boundary along a growth plane. If the two colours blur into each other in a swirl, treat it as heated or as two stones joined.
Smoky quartz shades toward brown-grey rather than orange, and irradiated smoky sold as citrine tends to look muddy. Orange calcite is softer, waxier and far lighter. None of these are frauds in themselves. The fraud is the label.
What to ask, and how to care for it
Ask the seller one question: is this natural or heat-treated? A good dealer answers immediately and prices accordingly, heated material is inexpensive and natural is not. A vague answer about energy or authenticity is an answer.
Once you own it, the good news is that heat-treated colour is stable and will not fade the way amethyst does in a window. It is water safe and salt tolerant. Handle geode points gently, because thermally shocked crystals chip more readily than untreated ones, and avoid dropping it on a hard surface.
Common questions
How can you tell if citrine (heat-treated amethyst) is real?
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White chalky base plus sharp orange tips equals heated amethyst, every time. Confirm it is quartz first with a glass scratch, then read the colour boundary. Treatment is permanent and not detectable by any consumer test other than colour distribution. A photograph cannot measure hardness, streak or specific gravity, so treat a visual match as a strong hint and run the physical test to be certain.
Is citrine (heat-treated amethyst) sold under the wrong name?
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Amethyst (or smoky quartz) roasted at roughly 400–550 °C, which converts the iron colour centres from violet to orange-brown. Stable and permanent; not a fake mineral, but a treated one, and it should be disclosed. It is not sold as treated in most shops.
Is citrine (heat-treated amethyst) treated, dyed or heated?
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Amethyst (or smoky quartz) roasted at roughly 400–550 °C, which converts the iron colour centres from violet to orange-brown. Stable and permanent; not a fake mineral, but a treated one, and it should be disclosed. It is not sold as treated in most shops.
What is citrine (heat-treated amethyst) confused with?
Its formula is SiO2, and it measures 7 on the Mohs scale. A hardness test against a known material is the cheapest way to rule out a substitute.
Check the rest of your shelf
Oraclite identifies any stone from a photo, flags the treated and mislabelled ones, and reads what each means for your actual birth chart. Free to start.