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How to Tell if a Crystal Is Natural, Dyed or Heated

By Jessica Woo, founder of Affinity Crystals · Updated 26 August 2026 · 5 min read

Let's start with the thing most articles about this get wrong: treated does not mean fake.

A huge amount of what's sold worldwide has been enhanced somehow, and much of it is perfectly good material honestly priced. The actual issue is disclosure — whether you were told, and whether you paid a natural-material price for a treated one.

Here's how to check for yourself.

Dyed material

The most common treatment you'll encounter, and the easiest to spot.

Dye needs somewhere to sit. It collects in fractures, along the porous banding of agate, and in any surface pitting. So:

• Look at the cracks. On dyed material, colour concentrates in fractures and reads noticeably darker along them. Natural colour doesn't follow cracks — it follows crystal structure.
• Check for impossible colours. Bright magenta, electric blue and neon green agate slices are dyed. There is no naturally occurring hot-pink agate.
• Look at the base of the piece. Cut and polished bases often show where the dye stopped penetrating.
• Suspiciously even colour across a whole large piece is a flag. Natural material almost always varies in saturation.

Commonly dyed: agate slices, howlite (frequently dyed blue and sold as turquoise), quartz, and magnesite.

Heat treatment

Heat changes colour permanently by altering iron in the stone. It's ancient, widespread, and generally stable.

The big one: most citrine on the market is heat-treated amethyst. This is not a scandal — it's the industry norm, and heat-treated citrine is real quartz that will stay that colour.

How to tell them apart:

• Heat-treated: tends toward a strong reddish or burnt orange, often with white or cloudy zones near the base of the point, and colour concentrated at the tips.
• Natural citrine: usually a paler, smokier, more muted yellow. It's far less common and priced accordingly.

If a large, deeply orange citrine cluster is cheap, it's heat-treated amethyst. That's fine — as long as it's sold and priced as such.

Glass and composites

This is the category that's genuinely not what it claims to be.

• Look for bubbles. Round internal bubbles mean glass. Natural inclusions have shape and structure — needles, phantoms, veils, fractures. Bubbles are spherical and obviously suspended.
• Temperature test. Quartz feels cool against the skin and takes time to warm. Glass and plastic warm almost immediately.
• Weight. Plastic feels wrong in the hand straight away — too light for its size.

Known glass products with crystal-sounding names: goldstone (glass with copper flecks), opalite (manufactured glass, not opal), and cherry quartz (usually dyed glass).

These aren't scams when sold under those names — goldstone is a legitimate and attractive material. It's a problem when it's presented as a naturally occurring stone.

The lab-grown category

Some material is grown rather than mined. Lab-grown amethyst and clear quartz exist and are chemically identical to natural material — often more flawless, which is itself the tell.

Whether that matters to you is genuinely a personal call. Some collectors care about origin and formation. Some people just want the object. Neither position is wrong.

Four questions worth asking any seller

1. Has this been treated in any way?
2. If it's citrine — heated or natural?
3. Where did this come from?
4. What is it actually called? (Not the marketing name — the mineral name.)

A seller who knows their material will answer all four without hesitating. That's really the test.

How we handle this

Our policy is simple: if a piece has been treated, we tell you. Dyed, heated, reconstituted — you'll hear it from us before you buy, not after.

We're not going to pretend nothing in the shop has ever been enhanced. Plenty of good material is. What we won't do is let you pay a natural price for a treated stone because nobody mentioned it.

Ask us about any piece and you'll get a straight answer. If we don't know something for certain, we'll say that too.

If you've bought something elsewhere and you're unsure what it is, bring it in. We'll look at it with you and tell you honestly, whether or not you bought it from us.

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