A bracelet of 8 mm beads on elastic is the entry point to gemstones for most buyers, and the point at which most substitution happens: glass for quartz, dyed howlite for turquoise, resin for malachite, goldstone for sunstone, synthetic for amethyst. The beads are small, the price is modest, and the buyer rarely has a way to check. A laboratory does, without unstringing.
What can be tested on a strung bracelet
Every bead visually. Under low magnification, each bead is examined for the tells of glass (round bubbles, swirls, mould seams), plastic (warmth, seams, softness), dye (colour concentrated at drill holes and in cracks), resin binders (granular texture, fluorescence) and mismatched beads. This sweep alone catches the majority of substitutions.
Polariscope, bead by bead. A small transparent or translucent bead held between crossed polarisers shows whether it is a doubly refractive crystal (quartz varieties, tourmaline, beryl), an aggregate (chalcedony, jade, lapis) or glass/plastic (dark or strained). Quick, and each bead can be checked.
Specific gravity of the strand. The bracelet is weighed and the bead volume calculated from count and measured diameter; the resulting density is compared with the expected value. Glass, plastic and resin bracelets give figures well off.
Refractive index on a sample. Beads with a flat spot or a polished surface can give a spot reading.
UV. The whole bracelet under long-wave UV reveals resin, adhesives, some dyes and some diagnostic fluorescences (synthetic blue spinel glowing red, for instance).
Magnification on a sample for natural-versus-synthetic questions in quartz and corundum beads, with the limits noted.
What cannot be fully determined
Natural versus synthetic in every bead of a quartz bracelet — a sample is examined and the finding stated for the sample. Origin. Precise RI on beads without a flat. Whether treatment such as heating was applied to every bead. A bracelet report describes what was tested and on how many beads.
Common findings
| Sold as | Commonly found |
|---|---|
| Clear quartz / sphatik | Glass |
| Amethyst | Glass; synthetic amethyst |
| Citrine | Heated amethyst; glass |
| Rose quartz | Glass; dyed quartz |
| Turquoise | Dyed howlite or magnesite; reconstituted |
| Lapis lazuli | Dyed jasper; sodalite |
| Malachite | Resin |
| Sunstone | Goldstone (glass) |
| Aventurine | Dyed quartz; goldstone |
| Tiger's eye | Fibre-optic glass |
| Black tourmaline | Black glass; obsidian |
| Jade | Dyed quartzite; serpentine; glass |
| Moonstone | Opalescent glass |
| Agate (bright colours) | Dyed agate (genuine but dyed) |
| Coral | Dyed or reconstituted coral; plastic |
| "Seven chakra" mixed strands | A mixture of dyed, glass and genuine beads |
What a bracelet report states
Bead count, diameter, total weight, the identification of each distinct material present (with the number of beads of each), treatments observed, imitations found, and a note of which tests were applied to which beads. Where a strand is mixed — genuine amethyst with two glass beads — the report says so.
Frequently asked questions
Do I have to unstring the bracelet?
No. Visual, polariscope, UV and strand-density tests are done strung. Only a sample SG needs a loose bead, and that can be skipped if the other tests are conclusive.
Is it worth testing a cheap bracelet?
If the purpose is to know what it is, the test is quick and inexpensive. If the purpose is to recover money on a cheap purchase, probably not.
Can a bracelet mix real and fake beads?
Yes, and it is common in mixed-stone "chakra" strands, where the expensive-looking beads are glass and the cheap ones genuine.
Are dyed beads fake?
Dyed agate or dyed quartz is genuine stone with added colour. It is mis-sold only if described as natural colour.
Can the laboratory tell synthetic amethyst in a bracelet?
On a sample of beads, usually, by twinning and zoning; very clean beads may be undetermined. The report says what was examined.