Two 8 mm onyx bracelets can cost the same and look nothing alike after a year. The difference is almost never in the stone, which is the same black chalcedony in both, but in how it was cut, drilled and polished. These are the four things we check in the workshop when a batch of beads arrives, and which you can check on any bracelet just by looking closely.
1. The lustre must be even
A well-polished bead reflects light equally all over. Turn it slowly under a lamp: if the reflection glides smoothly across the surface, without jumps, the polish is good. If you see matte patches next to shiny ones, or fine scratches running in one direction, the bead spent too little time in the tumbler or was polished with too coarse an abrasive.
Beware of the opposite too: a lustre that is too perfect, plastic-like, can mean the bead carries a coat of resin or wax. Natural stones shine, but with the texture of the mineral; onyx and hematite come close to a mirror, jasper and lava stay at a satin. If a lava bead shines, it is not lava.
2. The drill hole, clean and centred
Look at the hole. It should sit at the exact centre of the bead and have smooth edges, with no chipping. An off-centre hole makes the bracelet look twisted when closed; chipped edges cut the elastic cord from the inside and are the number one cause of bracelets breaking within months.
In quality beads the hole also has a constant diameter, 0.8 to 1 mm for gauges of 6 to 10 mm. If it is too wide, the bead dances on the cord; if too narrow, the elastic frays as it is threaded.
3. Calibration: they should all measure the same
An "8 mm" bracelet should have every bead between 7.8 and 8.2 mm. Lay the bracelet on a table and look at it in profile: the top line should be straight, with no teeth. Poorly calibrated beads give an uneven outline that shows more the darker the stone.
This has a cost: calibrating means discarding. From a batch of a thousand lapis lazuli beads, we set aside 15 to 20 percent for size. It is the reason two seemingly identical bracelets can carry very different prices.
4. Natural colour, with its variations
Natural stone is not uniform, and that is a good thing. Tiger's eye has bands that are more and less golden; agate shows rings; lapis lazuli carries flecks of pyrite and some white calcite. What should alert you is the opposite: beads that are all identical, in a colour that is too saturated, or with the tone concentrated in the cracks. Those are usually dyed.
Some treatments are common and honest if declared: turquoise is stabilised with resin so it does not crumble, and we say so on the product page. Others are not: "turquoise howlite" is howlite dyed blue, and coloured "onyx" does not exist in nature.
A quick test at home
Take the bead between your fingers. Natural stone is cold at first and takes a few seconds to reach hand temperature; glass and resin warm up instantly. Weigh it too: an 8 mm hematite bracelet is around 30 grams; if it weighs half that, it is probably "hematine", a ceramic compound.
Why it matters to us
We work with workshops in Jaipur and Bali that drill and polish by hand, in small batches, and that accept us returning the percentage that fails inspection. It costs more and takes longer. But a well-polished bead does not scratch, does not break the cord and still shines when the bracelet has birthdays. It is the difference between a piece for a season and one that stays.