KhyatiGems knowledge library
Amethyst
Purple quartz belongs to the same mineral species as citrine. Colour zoning and crystal form can be interesting features, but neither establishes natural origin or treatment status.
AI-assisted source review · 2026-10-16. No named gemologist review is claimed. How this reference was reviewed.
Lisa Ann Yount · CC0 · Source · CC0
| Material classification | Quartz |
|---|---|
| Mohs hardness (reference) | 7 |
Identity and appearance
Purple quartz belongs to the same mineral species as citrine. Colour zoning and crystal form can be interesting features, but neither establishes natural origin or treatment status.
Amethyst may be heated to alter its colour. Do not infer an untreated history from a deep purple photograph.
Care and handling
Keep prolonged intense light and heat out of the storage environment; ask for care advice that reflects any treatment.
Questions for an individual stone
Keep the material name, natural or laboratory-grown origin, treatment description and any report together. Ask which conclusions were established by examination and which remain unknown. The reference properties here describe a material; they are not measurements of a stone offered for sale.
If a description and report disagree, request clarification before making a decision. Photographs are useful for discussing appearance, but cannot authenticate a specimen. Keep care instructions with the item so that a jeweller or repairer can assess it before work begins.
Comparison and interpretation
Compare purple amethyst with yellow citrine as varieties of quartz, rather than as different mineral species. A stone showing purple and yellow zones may be described as ametrine, but a two-colour photograph does not settle its identity. Look at the distribution of colour through the whole stone under ordinary illumination. Reflections from a coloured backing or a strong photographic light can exaggerate the impression. For a cut stone, ask for views from the face, side and back so that a discussion about zoning refers to the same object.
Choosing and documenting a piece
A rough crystal cluster and a faceted amethyst answer different visual questions. The cluster illustrates growth and surface form; the cut stone illustrates how a cutter used the material. Do not compare their apparent clarity as though both were transparent finished gems. When considering a setting, ask about exposed points, existing fractures and cleaning. Keep amethyst away from harder stones in storage. If colour is the main reason for a choice, ask whether the photographs were corrected and request a neutral-light view.
Before making a decision
For amethyst, ask the seller to identify the actual item, state what remains unknown and explain the scope of any report. Keep photographs, measurements and written disclosures together. If an answer matters to your decision, obtain it before commissioning a setting or arranging a repair.
Sources and further reading
- GIA Amethyst reference Checked 2026-10-16