All articles · 2026-09-18

From a pencil sketch to a vector: jewellery drawings for CAD, catalogues and casting

A scanned or photographed jewellery sketch is grey, uneven and full of paper texture. How to turn it into clean line work for CAD, a catalogue or a laser engraver.

Jewellery design still starts on paper more often than not. The drawing then has to travel: into CAD for modelling, into a catalogue or price list, onto a laser engraver, or into an email to a client. Each of those wants line work — not a photograph of line work.

The example below is a pendant elevation — the kind of drawing that gets scanned at whatever setting the office scanner was left on, then saved as a JPEG because that is what the scanner does.

A line drawing of a faceted pendant: on the left the scanned copy with grey, uneven strokes; on the right the vectorized version with even black lines.
Left: the scan, 200 pixels, JPEG quality 70. Right: Line art mode, two colours. Every stroke is now a shape with a real edge — 51 nodes in total.

Line art mode, not Logo mode

A drawing made of strokes is a different problem from a badge made of filled areas. Line art mode is built for it: it follows the ink rather than treating each stroke as a region to fill, and it keeps the line weight even where the scan went pale. Set the colour count to two for a pencil or pen drawing on white — the ink and the paper.

The top of the pendant magnified: on the left the converging lines break up into grey pixel clusters; on the right they meet as clean straight strokes.
Where four lines converge at the bail. On the left the meeting point is a grey smudge — a CAD operator has to decide where it really is. On the right the lines meet at a point.

Getting a better scan is worth more than any setting

  • Scan at 600 dpi rather than 300 — it costs nothing and doubles what there is to work with
  • Scan, do not photograph: a phone photo brings perspective, uneven lighting and shadow
  • Save as PNG or TIFF if the scanner offers it; JPEG puts noise exactly where the lines are
  • Draw in ink, or go over the pencil in fineliner, if the drawing is going to be traced

What to export for each destination

  • CAD (Rhino, Matrix, RhinoGold) — SVG or DXF; DXF drops straight onto a construction plane
  • Laser engraving and marking — DXF for outlines, or SVG if the software prefers it
  • Catalogue, price list or lookbook — PDF, which keeps the geometry as geometry at any print size
  • Website or client email — SVG, which stays sharp on any screen and is a few kilobytes

One honest limit: a vectorizer traces what is on the paper. Hatching and shading come through as the marks they are, not as a rendered metal surface, and a drawing with an unclear line will produce an unclear path. It recovers the drawing, faithfully — it does not finish it for you.