Why your jewellery renders look flat

If your renders come back looking like a drawing of gold rather than gold, the instinct is to ask for better lighting. That is almost always the wrong place to look. Here is a job where the images were flat for a reason no lighting setup could have fixed.

The brief as it arrived

An ecommerce jewellery brand sent a reference image and their own CAD file for a round-brilliant eternity band, and asked for renders they could list with. They were a brand rather than a manufacturer, so the piece existed as a file, not as an object that could be photographed.

An eternity band is demanding to render for the same reason it sells well: it is almost entirely stone and reflection. There is very little plain metal for the eye to rest on, so anything wrong in the model shows up in every single image.

What was actually wrong

The metal in the supplied CAD was flat.

That word carries the whole problem, so it is worth being precise. Polished metal in a render does not really have a colour - it has a behaviour. It shows you the room around it. The bright edge running along a band, the dark line where a prong turns away from the light, the warm bounce between two stones sitting next to each other: all of that is metal reflecting its surroundings.

When a surface is flat, with no real curvature for light to travel across, there is nothing for those reflections to form on. Lighting can only give a surface something to reflect. It cannot give it somewhere to reflect it. That is why adding more lights to a flat model makes the images brighter without ever making them look like metal.

What was done

Nothing was rendered until the model was corrected:

• The CAD was rebuilt and re-set so the metal carried real, continuous form instead of flat faces.
• The geometry was smoothed, so light travels across the band and around each setting in an unbroken sweep rather than breaking at every facet of the mesh.
• Stones and metal were treated as separate objects, which is what lets a faceted stone refract and a metal surface reflect, each behaving as itself.
• Only then was the piece lit and rendered, in three metal colours.

The job went through three rounds of changes with the client before sign-off, and took about a week end to end - most of it the rebuild rather than the rendering.

What came out

This is the finished band, turning. A rotation is the honest test of the thing this page is about: watch the highlights travel along the shank and across each prong, and the darker band appear where the metal turns away from the light. That movement is the model reflecting its surroundings. The flat version could not do it from any angle.

Delivered as 1920 x 1920 px PNG and JPG stills and MP4 video through a download link on our own server, unbranded. The still set covered the same piece in three metal colours across multiple angles, graded so every image looks like it came from one sitting - which is what makes a set usable on a product page rather than a collection of separate pictures.

The client used the images on their website and in their catalogue.

The part worth taking away

The brief said render this CAD. The work was fix this CAD, then render it. A studio that renders only what it is handed would have delivered flat images and been technically correct about it.

So if your renders look wrong and more lighting is not helping, ask whoever is rendering them whether they checked the model first. If you are sending an existing CAD file, send it across and it gets checked before anything is lit.

Related services and guides

• Send your CAD file for rendering →
• Jewellery rendering service →
• STL vs 3DM: which file to send →
• 360° rotation videos →