Uneven colour is the first thing to look for. In real amethyst the violet is strongest at the crystal tips and fades towards the base. Amethyst is also 7 on the hardness scale, harder than window glass, so a steel blade slides off it. The usual imitations are dyed quartz, moulded glass and plastic, and they reach the market as cut stones and beads.
Every guide to spotting fake amethyst gives the same list. Look at the colour, check for bubbles, feel the temperature.
All of them name colour zoning. None of them says what zoning is or why it proves anything.
That gap is what this guide fills. It does not matter whether your amethyst is a ring, a pendant or a cluster on a shelf. The same thing gives it away.
I shape and set amethyst by hand in my Tbilisi studio. The stones I work with are crystal clusters rather than cut gems, and a cluster answers this question faster than a cut stone can.
Colour Zoning, and Why a Crystal Shows It Best
Amethyst is quartz, the same mineral as clear rock crystal. What makes it violet is iron inside the crystal and natural radiation in the rock around it. Both have to be there. That happened underground long ago and leaves nothing behind but the colour.
The crystal does not grow all at once. It builds up layer on layer over a very long time, and each layer takes up whatever iron was there when it formed. Some layers get more, some get less, so the colour is never quite the same all the way through.
That is colour zoning, and it has a pattern. Wikipedia puts it plainly: "the most intense color" is "typically found at the crystal terminations", the pointed ends. In ordinary words, the tips are the darkest part.
Violet tips, pale base
On a crystal you see this without doing anything. Look at a cluster and the points are violet while the rock underneath them runs pale, almost white. Every crystal in the group tells the same story.
Cut stones show it only from below
A faceted amethyst has the same zoning inside it. You just cannot see it from the top.
GIA describes the check that buyers use: they "view color zoning by placing the gems table-down against a white background". In other words, to see the zoning in a cut gem you have to turn it upside down onto paper.
GIA also sets the standard for faceted colour: "The finest amethyst color is a strong reddish purple or purple with no visible color zoning." That scale was built for cut gems, where the whole point is one even colour through the top face.
A crystal is a different object. There the zoning is not a fault. It is the record of how the stone grew.
Bubbles, Warmth and a Steel Blade
None of these needs equipment beyond a lamp.
Look into the stone with a light behind it. Round bubbles mean glass, because glass is poured and traps air as it cools. Colour gathered along cracks means dye, because dye soaks into stone the way water soaks into paper.
Hold it in a closed hand. Amethyst draws heat out of your skin, so it feels cold at first and warms slowly. Plastic and resin reach skin temperature almost at once. This one test removes the cheapest copies in seconds.
Use hardness in reverse. Amethyst is 7, window glass about 5.5. A steel blade or a copper coin leaves no mark on amethyst. Do this on the back or the rim, never on the display face, and never on a piece you are not willing to mark.
That last test is worth a word of warning, because it does not work everywhere. I had to warn against it in real versus fake obsidian. There the stone and the glass are about equally hard, so the test proves nothing. With amethyst the gap is wide enough to trust.
The same three checks carry over to the pink member of the family. I used them again in how to tell if rose quartz is real.
Four Things Sold as Amethyst
Three of them the checks above will catch.
Dyed quartz is white quartz with purple dye pushed into it. Moulded glass is pressed into shape, usually a faceted one. Plastic and resin turn up in cheap strings of beads. All three give themselves away on colour, bubbles, warmth or hardness.
Grown, not faked
The fourth is different. Synthetic amethyst is grown in a laboratory, in a sealed vessel under heat and pressure. What comes out is quartz with iron in it.
Not an imitation of amethyst. Amethyst, made faster.
Synthetic quartz is not a scandal in itself. The problem is selling it without saying so.
No home test separates it. Hardness matches, temperature matches, and it can even carry colour zoning. A laboratory settles it by looking for a growth pattern called twinning. The natural crystal has it and the grown one usually does not.
That said, keep it in proportion. The imitations that actually circulate are cut, moulded or strung as beads, which narrows the field for anyone holding a crystal.
Points That Stand Above the Rim
I shape each cluster to fit its setting and then stop. The crystal face stays as it grew, points and all.
That decision rules out one setting. A bezel is a smooth collar of silver folded down over the edge of a stone. It needs a stone that sits flat inside it.
A cluster does not sit flat. The points stand higher than the rim.
So the silver has to hold from outside instead. Beads stand up around the crown and grip the stone at its edge. Claws do the same job from above, closing over the corners and leaving the points clear.
Same choice, different reasons
I use the same approach on pyrite, where the flat crystal faces are the whole stone. Black tourmaline needs it for a different reason again: there the rim itself is broken.
Amethyst is hard enough at 7 to take daily wear without trouble. The setting is not there to protect a delicate stone. It is there to hold a shape that a bezel cannot.
Every amethyst I set is chosen for the crystal face, not for an even colour. They are in my amethyst collection.
Common Questions About Amethyst
Can amethyst go in water?
Yes. Warm water and a mild soap are fine, and a soft brush gets between the points. Dry it afterwards. Keep it out of ultrasonic cleaners.
How should I clean the crystal face?
A soft brush matters more here than on a smooth stone, because a crystal face holds dust between the points. Work the brush in one direction and rinse.
Will the colour fade?
It can, if you leave it in strong light for long enough. Amethyst loses tone with heavy light exposure, so keep the piece in a box or a drawer rather than on a sunny windowsill. Wearing it does not do this.
Why is part of my stone almost white?
That is the zoning. The pale part grew first, before much iron reached it, and the violet came later at the tips. No two clusters carry it the same way, so no two pieces look alike.
What happens if amethyst is heated?
Heat changes the colour. Amethyst turns yellow, orange or brown when it is heated, so a heated stone can end up looking like citrine. Heat it only part of the way and you get both colours in one crystal, which is called ametrine.
Is every purple stone amethyst?
No. Purple sapphire, tanzanite and purple fluorite are violet too. Fluorite gives itself away at 4, soft enough for a steel blade to mark it. Sapphire is far harder than quartz, and tanzanite sits close to amethyst, so hardness will not separate those two.
