How to photograph a mineral specimen honestly
Four disclosures make a specimen photograph honest: scale, axial light, the damage face, and unadjusted colour. Shoot the repair shot before the hero shot.
An honest mineral specimen photograph carries four disclosures: a scale in the frame in mm, a near-axial diffuse shot alongside the raking-light one, a view of the damaged face, and colour that has not been adjusted. Raking light flatters lustre and crystal habit; axial light is what shows bruises, fills and matrix repair.
In short
- Raking light sells and axial light discloses. A low side light at 20 to 30 degrees maximises the glitter on crystal faces and hides fills, glue lines and bruises. Near-axial diffuse light shows them. Take both, every time.
- Shoot the damage first. This is the whole discipline in three words. Photograph the bruised termination, the repaired arm and the sawn base before you photograph the good side, because the order you shoot in decides which images exist.
- A scale in the frame is not optional. A 3 cm thumbnail and a 13 cm cabinet piece are indistinguishable in a tight crop, and the commonest complaint about online buying is size, not quality.
- Colour: fix the white balance, then stop. Setting white balance from a grey card is measurement. Pushing saturation, shifting hue or dropping the black point is not. Green fluorite that arrives duller than the photograph is usually a saturation slider, not a lie about the species.
- Fluorescence photographs are a special case and need their own rule. State the band and the wavelength, state the exposure, and never composite a daylight and an ultraviolet frame without saying so.
| Property | Can a photograph show it? | What defeats it | The disclosure that fixes it |
|---|---|---|---|
| Size | Only with a scale in frame | Tight cropping; a background with no cue | A rule or scale bar in mm, in the same plane as the specimen |
| Colour | Approximately | White balance, saturation adjustment, screen calibration at both ends | Shoot a grey card, state that no hue or saturation adjustment was made |
| Lustre | Yes, and it is what photographs best | Nothing — this is photography's strength | None needed |
| Damage and bruising | Only under near-axial light | Raking light, which throws shadow into the bruise and reads it as texture | A second frame, diffuse and near-axial, of the same face |
| Repairs and fills | Sometimes, with effort | Raking light again; a matching background; a tight crop that ends at the join | An axial frame, a back view, and a written statement |
| Internal fractures | Rarely | Any surface-reflective lighting | Transmitted light where the specimen allows, or a written statement |
| Fluorescence | Yes, but the image is not comparable to any other | Long exposures, band unstated, composited frames | State band, wavelength, exposure and whether frames were combined |
The four disclosures, and why naming them helps
There is no shortage of advice on photographing minerals attractively. There is almost none on photographing them honestly, which is a different skill and the one that matters if the photograph is going to stand in for the specimen in somebody else's decision.
The four disclosures are: scale, light, damage and colour. A set of images that covers all four lets a buyer make the decision they would make with the specimen in their hand. A set that covers none of them is a picture of a mineral, which is a different thing.
Scale. A rule or a scale bar in millimetres, in the same plane as the specimen, in at least one frame. Coins and matchsticks are worse than nothing internationally. The size question is the commonest source of disappointment in online buying and it is completely solvable.
Light. At least one near-axial diffuse frame alongside the raking-light hero shot. The next section explains why this single addition does more than everything else combined.
Damage. Every specimen has a worst face. Photograph it. If there is a repair, photograph the join. If the base is sawn, photograph the saw marks.
Colour. Set white balance from a grey card and make no hue or saturation adjustment afterwards. Then say that is what you did.
None of this makes a specimen look worse than it is. It makes it look like what it is, which is the only defensible standard, and our page on what to look for when buying minerals online is the mirror image of this one, written for the person on the other end.
The two-frame test: raking light against axial light
This is a procedure rather than an opinion, and you can run it this afternoon on a specimen you already own.
Frame one, raking. Single light source, low, roughly 20 to 30 degrees above the plane of the specimen, coming from one side. Crystal faces that happen to be aligned with it flare brilliantly; everything else goes into shadow. This is the shot that sells, and every dealer photograph you admire is lit approximately like this.
Frame two, near-axial and diffuse. Light close to the lens axis, heavily diffused — a large softbox, or a sheet of tracing paper, or an overcast window. Flat, even, no drama. Nothing flares and nothing hides.
Now compare them. The things that appear in frame two and not in frame one are, in order of how often they turn up: bruises on terminations, where the crystal face is micro-fractured and reads as slightly milky under flat light and as ordinary texture under raking light; glue lines, which are specular in a different way from the mineral around them; fills and reconstructions, which have a matte, slightly soft surface; and old saw or trim marks on a base.
Raking light is not dishonest. Publishing only the raking frame is. The mechanism is well understood in the trade — our page on telling whether a specimen is repaired covers what the second frame reveals from the buyer's side. The point of taking both is that you cannot claim not to have known.
The sequence, from an empty table to a finished set
1. Clean the specimen only as far as you would sell it. Photographing a specimen cleaner than it will arrive is the first and most avoidable misrepresentation.
2. Find the worst face and photograph it. Near-axial, diffuse, with the scale in frame. Do this before anything else. The discipline is procedural, not moral: once the beautiful image exists on the card, nobody goes back for the ugly one.
3. Photograph the back and the base. Sawn bases, drilled mounting holes, old glue, and the label residue all live here.
4. Set white balance from a grey card under the light you are actually using, and leave it.
5. Now the hero shot. Raking light, dark neutral background, specimen at the angle that shows the form. Stop the lens down enough that the front and back of the specimen are both sharp — at macro distances this is the real constraint, and the physics is set out in the reference our microscope page cites. Focus stacking is legitimate: it changes depth of field and nothing else.
6. Scale frame. Rule in the same plane, sharp, readable.
7. Write the caption at the same sitting. Species, locality, size in mm, and the condition statement in plain words. A photograph and a caption written a week apart are how honest people produce misleading listings.
Finish state: five to seven frames — worst face, back, hero, one or two supporting angles, scale — and a caption that a buyer could read without the images and still know what they are getting.
What this actually costs, and where the line sits on editing
The honest accounting, because the method above is free to read and not free to run.
Equipment is the small part. A camera that can focus close, a tripod, one controllable light, a diffuser, a grey card and a millimetre rule. Focus stacking needs a rail or a lens with fine focus, and software. None of this is exotic.
Time is the large part. Seven frames, two lighting setups, a colour reference and a written caption is fifteen to twenty-five minutes per specimen once you are practised, and the first dozen take longer. For a collection of 300 pieces that is somewhere between 75 and 125 hours. That is the number nobody puts in the guides, and it is the reason most collections are photographed badly or not at all.
So the realistic answer for most people is a tiered one. Full treatment for anything leaving the collection or being insured. Scale-and-condition frames for everything else, which takes two minutes a piece and is the part that actually protects you. Nothing at all for the run-of-the-mill material, honestly recorded as unphotographed.
And the editing line, stated plainly. Legitimate: white balance from a reference, exposure, straightening, cropping that does not remove the scale, focus stacking, dust removal from the background. Not legitimate: hue shifts, saturation increases, black-point crushing that hides a fill, cloning out a bruise, or compositing a fluorescence frame onto a daylight frame without saying so. The test is whether the adjustment changes what a buyer would conclude about the specimen. If it does, it is a claim, and it has to be disclosed like one. If you are photographing to catalogue rather than to sell, the same standard is worth keeping anyway, because the person who inherits the catalogue is a buyer too — and if you are trying to source a specimen you cannot inspect in person, say so on a wanted list and ask for the axial frames by name.