Method
How the stones are photographed
Every gem dealer says their photographs are accurate. Here is the specification ours are taken to, so you can check the method instead of taking the pictures on trust.
The light
Colour is the product, and colour is a property of the light as much as of the stone. A sapphire photographed under a warm household bulb reads greener than it is; the same stone under a cool lamp reads greyer. So the light is fixed rather than convenient.
Stones are photographed at 5000–6500 K, CRI 95 or better — daylight-balanced, with a colour rendering index high enough that the light itself is not removing hues before the camera sees them. That is the same range the gemmological laboratories specify for assessing colour, and it is deliberately their number rather than one of ours.
Against a neutral grey card, never a coloured or reflective ground. No colour grading, no saturation adjustment, no selective editing of the stone. Photographs are resized and compressed for the web with chroma subsampling switched off — the setting that would otherwise smear exactly the colour information you are judging the stone by.
Stones that change colour
Alexandrite, colour-change garnet and colour-change sapphire are photographed twice: once at 5500–6500 K for the daylight face and once at 2700–3600 K for the incandescent one. Candlelight is not used, although some references allow it — it sits well below that range and exaggerates the red, which is manufacturing the change rather than showing it.
Both photographs are taken from an identical orientation, with only the lamp changed. A stone can be rocked to show two colours under one light by pleochroism alone, so a two-light pair is shot from an identical orientation with only the lamp changed. A pair shot from two different angles is showing you two faces of one stone and calling it something it is not.
What a photograph still will not tell you
No screen renders a gemstone exactly. Every monitor and phone is calibrated differently, and a stone’s colour genuinely changes with the light it is under — which is a property of the stone, not a failure of the photograph.
A photograph also cannot weigh a stone, measure it, or establish whether it has been heated. Those come off a scale, a gauge, and knowing where the stone was bought — which is why every listing states them separately from the pictures, and says how each is known.
Where a stone has a window, a soft extinction or visible colour zoning, the listing says so. Those are things a photograph can be made to hide, and hiding them is the most common way a gemstone picture lies.