Gemstone Photo Color Check

How to photograph a gemstone with accurate colour

1. Set up good light. Use bright, diffused daylight such as open shade or an overcast window. Turn off the flash and any beauty or colour filters.
2. Place a gray card beside the stone. Put the stone on a neutral background with a gray card or plain white paper next to it, in the same light and at the same angle.
3. Take a straight, sharp photo. Shoot from directly above at the same distance for both, avoid reflections of bright objects, and keep the stone in focus.
4. Upload the photo. Choose the photo in the tool above. It stays on your device.
5. Click the gray card. Click the middle of the gray card. The tool removes the colour cast so the card becomes neutral gray.
6. Click the gemstone. Click the body of the stone, away from sparkle. Read the corrected colour and download the corrected image if you want it.

What this tool does, and what it cannot do

The tool applies a simple white-balance correction. It reads the colour of your gray card and scales the red, green and blue channels so the card becomes neutral gray. Everything else in the photo shifts by the same amount, which removes most of the colour cast from the light.

It cannot tell you what a gemstone is, whether it is natural or treated, or how valuable it is. Many gemstones share the same colour. To identify a stone, measure its properties and use the Gemstone Identifier, the Specific Gravity Calculator and the Gemstone Comparator.

Why gemstone colour looks different in photos

Light sources differ in colour. Daylight in open shade is cool and bluish, while incandescent bulbs are strongly orange. Your eye adapts to this automatically, but a camera only guesses. A neutral reference in the picture gives the correction a fixed point.

Some gemstones also change colour with the light, such as alexandrite, which looks greenish in daylight and reddish in incandescent light. For those stones, state the light you used when you describe the colour.

Frequently asked questions

Why do my gemstone photos look different from the real stone?

Cameras guess the colour of the light, and the light itself changes the stone. Warm lamps push photos towards orange, shade pushes them towards blue, and phone cameras add their own processing. A gray card in the shot lets you remove the colour cast and get closer to the true colour.

What is a gray card and where do I get one?

A gray card is a flat card of neutral gray, usually 18 percent reflectance, that photographers use as a colour reference. Photography shops sell inexpensive ones. Plain matte mid-gray cardboard also works for rough checks.

Can I use white paper instead of a gray card?

You can, but results are less reliable. Many papers contain optical brighteners that add a blue tint, and white areas easily over-expose. A mid-gray card is better because it stays within the camera's range.

Does my photo get uploaded anywhere?

No. The photo is read and processed entirely in your browser on your own device. It is never sent to a server.

Can this tool identify a gemstone from a photo?

No. Many different gemstones share the same colour, so a photo cannot identify a stone or judge its quality, treatment or origin. To identify a stone, measure its refractive index and specific gravity and use the Gemstone Identifier and Specific Gravity tools.

What is the best light for photographing gemstones?

Bright, diffused daylight, such as open shade or a window on an overcast day, gives the most reliable colour. Avoid direct sun, which causes harsh reflections, and avoid mixed lighting from lamps and windows together.