How to Tell If a Rock Might Be Valuable: Reading Rough Stones in the Field

Rough gemstones look nothing like the jewellery-shop photos - a sapphire fresh from the sieve looks like a dull bit of bottle glass, which is exactly why beginners throw keepers back. Here's how to identify gemstones in the rough before you do.

What Rough Gemstones Actually Look Like

• Forget sparkle - rough stones are waxy, greasy or glassy, often coated in a dull skin. The magic word is lustre, not shine.

• Sapphire in the sieve: dark, often nearly black until wet and held to the sun, when blues and greens glow through.

• Rough gold doesn't glitter - it glows a rich, buttery yellow that stays the same in shade. The glittery stuff in the pan is usually mica or pyrite.

• Wet everything. Water is the field test that costs nothing and reveals the most.

Simple Field Tests: Weight, Hardness, Streak and Light

Weight

Gem minerals are dense - a keeper feels heavier than a same-sized pebble. Gold feels absurdly heavy; that's the whole basis of panning.

Hardness

Sapphire scratches glass and steel effortlessly; quartz scratches glass too. Scratch the stone's least attractive corner - not its face.

Light

Hold candidates to the sun - gem material glows, transmits or flashes colour; ordinary rock stays mute.

Streak

Rubbed on unglazed ceramic, pyrite streaks greenish-black while gold streaks gold - the classic fool's gold test.

Keep the Is It a Keeper? Rock ID Field Card from our Resources page in your kit for these tests.

The Lookalikes That Fool Everyone

The usual fakes

Pyrite and mica for gold; smoky quartz for sapphire; coloured bottle glass (old diggings are full of it) for absolutely everything.

The reverse mistake

This one matters more: zircons, garnets and sapphires get discarded as "just gravel" because they're small and dull when dry.

When to Take a Closer Look at Home

• The field rule: if it's heavy, hard, or glows - jar it. Sort in good light at home with a loupe and clean water.

• For a promising stone, get a real identification. Local lapidary clubs (find one through AFLACA) will often tell you in thirty seconds what the internet couldn't in three hours, and some state museums can help too. What comes next is in What Happens After You Find a Gemstone?.

Managing Expectations Without Killing the Fun

• Most of the jar will be pretty-but-worthless - and a jar of pretty is still a good day.

• Genuine cutters do come out of public ground every season. Not knowing which sieve holds one is the entire appeal.

Want more keepers in the jar? Start with How to Read the Ground: Where Gemstones and Gold Actually Collect and Fossicking Tips for Beginners: What Nobody Tells You First Time Out.

Link to downloadable resource: Is It a Keeper? Rock ID Field Card

You'll find four thirty-second tests: wet it, weigh it, scratch it, hold it to light. Download or print the PDF with full details and keep it in your kit. The phone download version is a quick overview reminder list.

Sources: field tests are standard mineralogy. For more on Australian minerals, see Geoscience Australia. Find a local lapidary club through AFLACA.