Amethyst crystal cluster
Look at the purple crystal tips, the cluster and its base. Colour alone does not establish natural origin or treatment history.
Inspect the full-resolution details ↗ROCKS, MINERALS & CRYSTALS
Rocks, minerals & crystals: a collecting guide
Start with what you can see. Compare the shape, crystal tips and surface before attaching a name or a price.
This guide uses three documented reference photographs and a five-part collecting checklist. Reference specimens are not a diagnosis of your object.
CuriSnap · · Collecting guidance, not laboratory identification.
Compare the specimens ↓What is the difference between a rock and a mineral?
A mineral is a naturally occurring inorganic material with an ordered internal structure and characteristic composition. A rock is an aggregate of minerals or mineral matter. Start a collection record with that distinction instead of treating every shop name as a mineral species. USGS ↗
What do the reference specimens actually show?
Open each original photograph to inspect details. Amethyst is a purple variety of quartz; colour does not identify every purple stone. Compare the examples as documented objects, not as proof of your specimen’s chemistry. GIA ↗
Rock crystal / clear quartz
Compare the projecting crystal faces and tips, not just transparency. The source describes this specimen as rock crystal from Brazil; that locality does not apply to your find.
Inspect the full-resolution details ↗
Dyed agate slice: a treatment example
The source explicitly describes a coloured slice made into a coaster. Study the band pattern, but do not use its blue colour as a natural-colour reference.
Inspect the full-resolution details ↗What should you record before comparing prices?
Use the checklist below for each specimen. If a seller record omits size, condition or treatment, keep the uncertainty visible instead of borrowing its price.
| Factor | Record | Next check |
|---|---|---|
| Crystal form and completeness | Main crystals, tips, chips and reverse | Photograph the whole outline and visible damage |
| Size and form | Length, width, height; cluster, single crystal or polished piece | Do not compare different forms by weight alone |
| Colour and associations | Neutral-light photos, base and associated material | Record lighting and seller treatment disclosures |
| Locality and provenance | Original labels, receipts and seller statements | Separate documentation from inference |
| Market records | Original URL, currency, date and condition | An asking price is not a sale or net proceeds |
What should you ask about treatments and imitations?
Ask the seller to disclose dyeing, heating, coatings, glue and repairs, and save the answer with the listing. The blue agate photograph above is a documented treatment example. An unremarkable photograph does not certify an untreated specimen.
Review the labelled agate example ↑How should you photograph and care for a find?
- Whole specimen: use a neutral background and diffuse light; include the base.
- Details: record faces, texture, reverse and visible damage without retouching it away.
- Scale: include a ruler and record length, width and height separately.
- Labels: photograph original labels and separate seller statements from verified provenance.
For identified amethyst, GIA advises warm soapy water and warns against steam cleaning; prolonged intense light can fade some material. Do not extend this advice to unidentified minerals or mixed specimens. GIA ↗
Start with your photographs →Common collecting questions
Can a photograph confirm a mineral?
A photograph can document shape, colour and visible damage. It does not measure hardness or chemical composition. Keep an identification as a candidate until the relevant checks support it.
Does a bright colour mean the stone is dyed?
No. Ask for treatment disclosure and compare the actual specimen with documented references. Our blue agate example is labelled as treated because its source says so, not because colour alone proves dyeing.
Can I price a specimen from these photographs?
No. These are identification references, not sale records. Compare form, measurements, damage, attribution and documented provenance against dated listings or completed sales.
Sources and further reading
- USGS: rocks and minerals
- GIA: amethyst
- GIA: amethyst care and cleaning
- How to research comparable sales
- Methodology and limitations
Prepared by CuriSnap. Photograph credits and licences appear beside each image. These references are educational; this page is not a specimen certificate and makes no medical or healing claims.