Is your citrine real, or heat-treated amethyst?
Here's something most crystal shops won't tell you: the bright orange "citrine" you see almost everywhere isn't citrine at all. It's amethyst that's been baked until it changed colour.
That's not a fringe problem. By most accounts in the trade, the large majority of "citrine" on the market is heat-treated amethyst, and natural untreated citrine is comparatively rare. The deep golden-orange most people picture when they hear the word is almost always the treated version. None of this is a scandal in itself; heat treatment is a long-accepted practice, though disclosure of it is expected. It only becomes a problem when a piece is sold as something it isn't. That's the gap this guide closes, so you can know exactly what you own.
First, what citrine actually is
Citrine and amethyst are the same mineral: quartz, which is silicon dioxide. They are colour varieties of it, the way the same grape can become very different wines. Both sit at 7 on the Mohs hardness scale. The difference between them is colour, and colour in quartz comes down to trace elements and the conditions the crystal formed in.
Amethyst gets its purple from an iron-related colour centre that requires both iron impurity and natural irradiation to form. Heat changes that. When amethyst is warmed past a certain point, the colour centre is destroyed, the iron rearranges, and the purple gives way to yellow, then orange. The earth can do this slowly through geological heat, which is how genuine natural citrine forms. A furnace does it in hours, which is how most "citrine" on the shelf is made.
Worth being honest about one detail: the exact cause of natural citrine's colour is not fully settled in the scientific literature, with the colours of amethyst, citrine and prasiolite all linked to iron but the precise mechanism still debated. Anyone who tells you it is definitively one single thing is overstating what is actually known. What is well established is the treated version: heating drives a change in the oxidation state and configuration of the iron impurities, and that is what produces the colour.
The temperature, for the curious
If you like the specifics, the colour change happens in stages. A peer-reviewed 2020 study in Scientific Reports found that heated amethyst holds its purple below about 420°C, passes through a narrow prasiolite (pale green) stage between roughly 420 and 440°C where the colour centre is least stable, and turns to citrine above about 440°C, with around 560°C being a practical temperature to produce a good citrine colour. Same crystal, three different looks, set by temperature.
How to tell the difference
You don't need lab equipment for most of this. Once you know what to look for, the tells are surprisingly easy to read.
Look at the base. This is the single most useful sign. Amethyst grows as purple tips on a white or greyish quartz base. When it is baked, only the tips take on the orange colour; the base tends to stay stark white. So if you are looking at a bright orange cluster with an obviously white bottom, especially with a sharp line between the white and the orange, you are very likely looking at heat-treated amethyst. Nature rarely draws a line that abrupt.
Read the colour honestly. Natural citrine is subtle. Think pale honey, white wine, champagne, sometimes a smoky or faintly greenish yellow, and usually a fairly even colour throughout. Heat-treated amethyst is louder by comparison: vivid orange, reddish-orange, deep amber, often with the colour concentrated at the tips and fading toward the base. If a piece is a bright, saturated orange, that intensity is itself a clue. Genuine citrine in that colour exists but is the exception.
Check the form. Natural citrine usually appears as single points or modest clusters, more like clear quartz in habit. It very rarely forms as geodes. So those orange "citrine geodes," and pieces that look cut from the inside of a geode, are a classic giveaway of treated amethyst, because that is exactly what they started as.
The one technical test: dichroism. Natural citrine is dichroic, meaning it shows two slightly different shades depending on the angle you view it through under polarised light. Heat-treated amethyst is not dichroic and looks the same colour from every angle. Here is the caveat most guides get wrong, and it is an important one: this is a one-way test. If a stone is dichroic, that is strong evidence it is natural. But the absence of dichroism does not by itself prove a stone is good, and some artificially coloured quartz can still show dichroism, so the test is best used to confirm "natural," not to condemn a stone. Seeing it properly needs a small tool called a dichroscope.
What won't help: the hardness test. Because both are quartz, both sit at Mohs 7. Scratching tells you nothing. Anyone suggesting a scratch test to separate citrine from treated amethyst is leading you wrong.
Does it actually matter?
That depends on what you want, and we will be straight with you rather than push a verdict.
If you simply love a warm orange quartz on your shelf, heat-treated amethyst is a real, natural stone that has been through a real process; it isn't glass or plastic, and there is nothing wrong with owning it. Where it matters is honesty and price. Natural citrine's rarity means it tends to command more, so the real harm is paying a natural-citrine price for a treated piece, or being told something formed in the ground the way it looks when it didn't. Knowing which you have lets you decide what it is worth to you.
How we handle it
Every piece we sell is described as exactly what it is. If something is heat-treated amethyst, we say so; we don't relabel it as natural citrine to charge more. If a piece is genuine natural citrine, we tell you where it is from, because with citrine, provenance and honest colour are most of the story.
That is the whole idea behind how we work: you should never have to reverse-engineer what you bought. Know what you own.
Sources: Cheng, R. & Guo, Y. (2020), "Study on the effect of heat treatment on amethyst color and the cause of coloration," Scientific Reports 10:15805. Mineral identification and dichroism points cross-checked against Mindat.org and gemmological references. Treatment and disclosure norms per gemmological trade sources.