Turquoise identifier by photo

The turquoise identifier compares photos of a blue or green stone, bead or piece of jewelry and suggests possible matches. Upload one to three photos of the same stone: the whole stone in daylight, the back, an edge or a drill hole, and a close view of the matrix. Then choose the form that fits: rough nugget, cabochon or bead, set in jewelry, or not sure.

The result lists what the stone may be, the visible clues behind each candidate and the imitations or natural lookalikes still in play. It also says what the photos could not settle, which for turquoise always includes treatment and source. A follow-up question comes last; answer it or ask your own. Where you bought or found the piece is the most useful note you can add.

Much of what is sold as turquoise is treated or is not turquoise at all, so the turquoise identifier describes what the photo shows and leaves treatment open. Natural turquoise is a fine-grained, slightly porous copper mineral, opaque and sky blue to green. GIA explains that lower-quality turquoise is bonded at the grain level with polymer resins to make it more stable. That stabilized stone is still turquoise, but a photo cannot tell it from untreated material, so the name becomes “turquoise, treatment unknown.”

Reconstituted or block turquoise is made from chips or powder pressed together with a binder, often with dye. GIA also notes that turquoise is often imitated by dyeing common, inexpensive minerals such as howlite or magnesite. Plastic and resin imitations are common in low-cost jewelry.

Matrix is the host rock caught in the turquoise. GIA describes it as dark brown from limonite or tan from sandstone, in patches or veins; fine web-like seams are called spiderweb matrix. In natural stone the matrix is a different and often softer material, so after polishing it tends to sit in slightly low channels. Tilt the stone toward a window and photograph it at a low angle to show this.

Matrix lines that look painted on, pressed in or perfectly level with the surface fit reconstituted turquoise. Gray-black web veins in a white or gray stone dyed blue fit dyed howlite or magnesite, especially when the blue is darkest along those veins. A sharp close-up of the matrix is the most useful single view the turquoise identifier can get.

Fine, dense turquoise takes a waxy polish, and GIA notes that coarser, more porous stone looks dull. A very glassy, even shine on a light stone can point toward plastic or resin. Then look at how the color spreads. Natural turquoise usually varies gently across a piece, from bluer to greener patches. Very even color with a fine chip or granular texture fits reconstituted material.

Color that collects in cracks, veins and pits is a sign of dye. In dyed howlite or magnesite the cracks often show a deeper blue than the rest of the stone. A bright, perfectly uniform blue with no texture at all keeps imitation candidates on the list.

Edges, chips and drill holes show what lies under the surface. White or pale gray inside a drill hole or chipped edge points toward dyed howlite or magnesite, because the dye has not reached all the way through. Glossy, uniform beads that feel very light and warm, with mold seams or small bubbles, point toward plastic or resin. Bubbles in a glassy piece point toward glass. Photograph one bead hole or chip in sharp focus in daylight.

Use only safe checks: daylight, a ruler or coin for scale, and how heavy the piece feels for its size. Do not scratch, file or heat the stone, or wipe it with solvents. Those tests damage treated stones and jewelry, and the answer still needs a lab. GIA explains that gemological labs use infrared spectroscopy to find polymer resins and to separate turquoise from dyed imitations.

Some lookalikes are natural minerals, not imitations. They are real stones that simply are not turquoise.

For a rough crust or a loose specimen, the mineral identifier compares a wider range of minerals.

Kingman, Sleeping Beauty, Persian, Royston, Hubei and Number 8 are names buyers often see. A photo cannot read any of them. Turquoise from different mines can share a look, and GIA notes that the trade calls an even, intense blue “Persian blue” whether or not it was mined in Iran. The turquoise identifier describes the look instead, such as “even sky blue without matrix” or “black spiderweb matrix,” and keeps the mine as the seller’s claim.

The Federal Trade Commission advises that sellers should disclose treatments that are not permanent, need special care or significantly affect value. Sales paperwork should include what the seller told you about origin and treatment; if a seller will not put that in writing, the FTC suggests working with someone else. A gemological lab can test a stone for treatment and imitation.

Suppose a bead looks evenly blue in a seller photo, with a dark line at one end. That image leaves open natural turquoise, treated turquoise and several imitations. In daylight, photograph the line and the existing drill hole from different angles. A pale interior or a seam would add clues, while glare may hide both. Use the same camera settings for the whole bead and the close-up so the color is easier to compare. A lab can address treatment when it matters to a purchase.