Some of the prettiest stones in any crystal shop were made in a furnace, and some natural stones are dyed, heated or coated before they reach you. None of that makes a stone bad. It only matters that you know what you're holding. This guide covers the man-made and treated stones you'll meet most often, and the simple checks you can do at home.
Man-made stones (and why people still love them)
- Opalite: glass made to glow milky blue against dark backgrounds. It is not opal, and it is not natural, though it's a favorite for its soft glow.
- Goldstone: glass filled with sparkling flecks of copper. The story goes that it was first made by accident in a Venetian glassworks.
- Blue sandstone: the deep blue form of goldstone, glass with silvery sparkle. Despite the name, it isn't sandstone.
- Cherry quartz: red or pink glass with streaks, sold under a quartz name. It isn't quartz.
- Bright blue, green or rainbow "obsidian" in perfect colors: usually man-made glass. Natural obsidian is mostly black, sometimes with gray snowflakes, golden sheen or red-brown swirls.
Our guides name man-made stones plainly, so you can choose them for what they are.
Natural stones that are often treated
- Citrine: much of the citrine on the market is heated amethyst. Heated stones are burnt orange with a whiter base, often still in cluster form. Natural citrine is pale lemon to soft honey, with the color fairly even.
- Turquoise: howlite and magnesite are often dyed blue to imitate it. A chip or scratch that shows white underneath, or color collected in the cracks, gives it away.
- Aura quartz: real quartz bonded with a thin film of metal such as titanium or gold for its rainbow shine. The quartz is natural, and the color is added.
- Red tiger's eye: often golden tiger's eye that has been heated.
- Bright pink, purple, blue or green agate: almost always dyed. Natural agate comes in white, gray, brown, red and soft blue bands.
- Very green "jade" at a low price: often dyed quartzite or glass. Nephrite jade is a softer spinach green and feels heavy and cool.
Simple checks you can do at home
- Look closely. Under a magnifier or a phone's zoom, round bubbles or swirl lines point to glass. Most natural stones show tiny flaws, crystals or uneven color instead.
- Check the cracks. Dye gathers in cracks and pits, leaving them darker than the rest of the stone.
- Hold it. Quartz and most natural stones feel cool and stay cool for a moment. Glass and plastic warm up quickly in your hand. It's a rough hint, not proof.
- Consider the color. Colors that look too bright and perfectly even, especially at a low price, deserve a second look.
- Scratch test, with care. Quartz (7 on the Mohs scale) scratches window glass, and glass (about 5.5) doesn't scratch quartz. Only try this on a hidden spot of a piece you don't mind marking.
- A cotton swab test for dye. A swab with a little acetone, rubbed on a hidden spot, picks up color from many dyed stones. It can dull a finish, so keep it small.
When a stone matters to you, buy from a seller who tells you what it is, and ask. You can always ask us about any piece in our shop.
Further reading
Turquoise vs dyed howlite from Rock Identifier is a careful, well-sourced look at telling those two apart, including why a photo alone can't settle it.
Is a man-made or treated stone still worth having?
That's a personal choice. Many people love opalite and goldstone for their glow and sparkle, and work with them in the same way as natural stones. What matters is knowing which is which, so the price and the story match the stone. For care, see the crystal care chart, and for every stone's meaning, the crystal meanings A–Z.