Why a little detective work pays off

Quartz is the most common mineral in the Earth's crust, and for most collectors it's where everything begins. A bowl of tumbled stones from a seaside shop, a lucky find on a Cornish beach, a gift from a friend who "thinks it's rose quartz" — before long you have a small crowd of stones that all look slightly related and no clear way to tell them apart. The good news is that quartz varieties are generous with clues. Once you know what to look for, most of them announce themselves within seconds.

This guide covers the three you'll meet most often: clear quartz, rose quartz and smoky quartz. With each one, the aim is to recognise the real thing confidently and to spot the lookalikes that commonly sneak into collections.

Clear quartz: the shape and the shine

Clear quartz — often called rock crystal — is colourless, transparent and blessedly honest about itself. Look first for crystal faces. A natural point will have flat, slightly waxy-looking faces meeting at defined edges, usually ending in a six-sided pyramid. Glass imitations have a soft, rounded quality to their edges and often tiny round bubbles inside.

Hold a clear piece against a printed page. A well-formed crystal shows a slight doubling of the lines underneath, because quartz splits light into two paths. This is most visible through a flat polished face, and it's a reliable tick that glass rarely gives you.

Other markers worth knowing:

• Hardness of 7 on the Mohs scale — quartz scratches window glass, and steel won't scratch quartz. Test only on a hidden corner of a rough specimen, never on a polished favourite.
• Cool to the touch and slow to warm — it draws heat from your hand noticeably.
• Internal wisps and veils — natural crystals almost always carry some cloudiness, fractures or needle-like inclusions. Perfect clarity in a large piece is uncommon and worth questioning.

Watch out for cut glass and for white topaz or beryl. Topaz feels slightly heavier and often shows a faint golden or pink tinge; beryl has a softer, more greasy lustre.

Rose quartz: colour with a soft edge

Rose quartz is a different animal entirely. Where clear quartz is glassy and sharp, rose quartz is cloudy and usually translucent rather than transparent, with a colour that ranges from pale blush to a deeper dusty pink. That milkiness isn't a flaw — it comes from fine fibrous inclusions that scatter light through the stone, and it's one of your best identifying features.

Natural rose quartz is very rarely found as neat, sharp crystal points. You'll mostly see it as masses, tumbled pebbles, carved hearts and beads. If someone offers you a perfectly formed, transparent pink quartz point, treat it with suspicion — you may be looking at pink glass or a dyed crystal.

Useful distinctions:

• Rhodonite is pink with black veins or blotches, and much more opaque.
• Rhodochrosite has banded white and pink layers, like bacon.
• Pink opal and pink halite are lighter, softer and will not scratch glass.
• Dyed glass is often uniformly bright, with colour pooling in cracks and a tell-tale ring when tapped.

Sunlight fades rose quartz over years, so keep your best pieces out of a bright windowsill.

Smoky quartz: brown, grey and deeply variable

Smoky quartz runs from a pale champagne grey to a rich cognac brown and through to almost black. The colour comes from natural irradiation acting on traces of aluminium inside the crystal structure, which is why the tone often deepens towards the tip and fades near the base. That gradient is a wonderfully natural signature.

Smoky quartz keeps the same hexagonal form and glassy lustre as clear quartz, and its transparency varies from nearly clear to fully opaque. Common confusions include:

• Black tourmaline (schorl) — opaque, with fine lengthwise striations and a duller, more matte surface.
• Obsidian — volcanic glass, so it fractures in smooth curved shells and never shows flat crystal faces.
• Smoky glass — uniform in colour, often with bubbles and moulded seams.
• Heated amethyst — many "smoky" pieces sold cheaply are amethyst turned brown in a kiln, usually with a slightly reddish or yellowish cast and no colour zoning near the base.

Simple tests you can do at the kitchen table

You don't need a laboratory. A few everyday checks will settle most arguments.

• A bright torch or phone light. Shine it through the stone from behind. Inclusions, colour zoning and growth lines become visible, and glass tends to look unnaturally even.
• A hand lens or jeweller's loupe. Ten times magnification reveals crystal faces, striations and bubbles that the naked eye misses.
• Hardness. Quartz scratches glass. Glass, calcite and halite do not.
• Heft and temperature. Quartz feels cool, dense and substantial for its size compared with plastic or resin replicas.
• Streak. Rubbed on unglazed porcelain, quartz leaves no coloured streak — helpful for ruling out hematite and other lookalikes.

Work from the outside in: shape and surface first, then colour, then light, and only then the scratch test if you're still unsure.

Building confidence over time

Keep a small notebook, however informal. Note where each piece came from, what you paid and which features convinced you. Label your specimens with a little paper tag or a dab of enamel paint on the base. Handle everything often — the more quartz you handle, the more quickly your fingers and eyes learn the weight, the coolness and the particular soapy sheen of a freshly fractured surface.

And do keep a couple of known reference pieces to hand: one clear point, one rose pebble, one smoky crystal. Comparing a mystery stone side by side against a confirmed one beats any written description. If a piece still refuses to give up its secret after all of that, enjoy it as what it is — a lovely stone with a story you haven't quite finished reading.