Gems are among the most fun objects to create in 3D. In this tutorial, I’ll show you how to create simple gems, including a lathed cabochon and a subdivision gem.
Setting the scene up
We’ll start by setting the scene up. We`ll use the Tile Platform preset.
Next, we’ll change the visible background to None, as the black background will give us better contrast.
We´ll leave the lights as they are.
Modeling the cabochon
We`ll do the cabochon cut first. It is nothing more than a simple lathe.
- Set the window to Front view (5 key).
- Press the Z key to activate the grid
- Set the perspective to orthographic
- Draw 3 points using the pen tool, as shown in the image below.
- Lathe the resulting profile.
That’s all the modeling we need.
Place the cabochon on the “floor” and set up a camera. The image below is rendered using the Raytracing: Better preset.
Now we need a texture.
Texturing
Gems are transparent, most of the time. We’ll stick to that here.
Gems have relatively high refraction indices.
Let’s create a new image texture with the following settings:
Let us use a Fresnel interpolator for the reflectivity. This will give us a more natural behavior.
The result of this texture applied to the cabochon we just made should be something like the image below.
Underwhelming, isn’t it?
Reflections and transparencies depend on the angles in which light interacts with the objects. Scatter some copies of the gems on the scene and re-render.
Rendering
Something is amiss. These aquamarines look like plastic.
Let us increase the Reflection Bounces in the Render dialog settings (Ctrl+R or Cmd+R)
The default in the preset we are using is 2.
With 4 bounces things look better.
Now, let’s try 8 bounces.
Faceted Stones
Faceted stones are often more interesting than round stones because of the planes that break and bounce the reflected light.
Let us start by converting a cabochon to its polygonal equivalent.
- First we´ll convert the lathe into a Bezier surface
- We´ll simplify the Bezier surface
- Then, we’ll convert the Bézier surface into a Polygon mesh
- Then, we set the auto smooth angle to 0º and we get the polygonal equivalent.
The facets look good, but we don’t have enough yet.
We will create more facets in the polygonal modeler using the bevel tool.
- Double-click on the polygon mesh to enter the Polygon modeler
- Select the point on the tip of the gem
- Using the Bevel tool, click and drag to create a new face
- Repeat on the other tip.
- To create a “neck” for the stone, we´ll bevel a loop selection. First we need an edge selection, so select one of the edges on the neck and then press L to create a loop selection.
- With this loop selection, we create the neck by dragging with the bevel tool.
This is a good way to create simple faceted stones.
In an upcoming tutorial we will tackle more elaborately shaped gem stones. I hope this will be of use.
Please share your successes or questions!
