A bangle size is its inner perimeter: size 16 means 160 mm. What remains is knowing which length and width give that perimeter, how much wire to cut, and what the piece will weigh.
The inner perimeter, in centimetres. Size 16 means 160 mm.
Densities are the ones used by the material cost calculator.
The most common shape in fine jewellery. Its perimeter has no closed form: it is approximated using Ramanujan's formula.
1.00 gives a round bangle. The higher the value, the flatter it gets. The default is derived from jewellers' published dimensions, it is not a standard.
It does not change the size, but it changes the outer footprint and the weight.
Wire length is not the inner perimeter. As the wire bends, its inner face compresses and its outer face stretches: only the middle fibre keeps its length. That is what is measured here.
The weight assumes a round wire section. A half-round, a square wire or a shaped profile has a different area, hence a different weight.
Three reasons make converting a bangle size into dimensions less obvious than it looks.
Three acknowledged limits, so the numbers can be used knowingly.
About bangle size, shape and weight.
An inner perimeter, expressed in centimetres: size 16 measures 160 mm around. The word « circumference » is often used but it is improper as soon as the piece is not round, which is the case for most fine jewellery bangles.
For a bangle with a clasp, measure the wrist with a paper strip or a tape measure, without tightening, then add the desired ease. For a rigid bangle with no clasp, the measurement that matters is not the wrist but the passage over the hand, hand closed and thumb tucked into the palm.
Because a bent wire only keeps its length along its middle fibre. Its inner face compresses, its outer face stretches. The length to cut is therefore measured at mid-thickness, which adds roughly π times the wire diameter to the inner perimeter.
A stadium has straight flanks where an ellipse curves in gradually: at equal dimensions its perimeter is slightly longer, by about two per cent. On a size 18 that is roughly three millimetres, a third of a size. It is small, but it is measurable.
It is a theoretical weight: wire section, middle-fibre length, alloy density. It accounts for neither the clasp, nor the solder joints, nor any decoration or stone setting. On a plain piece it is close to reality; on a worked piece it gives an order of magnitude.
Liink connects jewellery brands with their workshops: orders, production tracking, metal weight account and the French statutory register.
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