What is it?

With parametric CAD we model designs in such a way that, once finished, we can modify their dimensions immediately. The new version will differ from the original only in the modified parameters. For example, if we have created a ring for a gem with certain measures, we can create any variation of that ring with other gem measures without modifying the rest of the measures. If during modeling we have established that other dimensions of the ring are related to the size of the gem, these dimensions will also be modified automatically, without requiring remodeling tasks. To do this, simply we change the value of the gem parameters (such as width, length, and height), and immediately we obtain the new version.


What is its purpose?

Parametric CAD can be applied to:

  • A CAD model from which various parts are to be manufactured but with variations in one or more dimensions. The most common case in jewelry is the variation of the finger size for a certain model.
  • A CAD model of which only one version will be manufactured, and yet before manufacturing it is intended to evaluate variations of the prototype in order to select the most suitable version.
  • Partial parametric modeling. It consists of combining direct CAD modeling and parametric CAD modeling techniques, in such a way that the most common CAD operations are parameterized, and the least common or exclusive are modeled with direct CAD.


Comparison of parametric CAD versus direct CAD

Generally speaking - and perhaps somewhat crudely - direct CAD is simpler and faster, and parametric CAD is slower and more technical. Direct CAD will be cheaper for simple projects, and parametric CAD cheaper for complex projects.

  • For a prototype of which only one version will be manufactured, parametric CAD requires more modeling time than direct CAD.
  • Once the prototype is designed, the parametric CAD allows you to explore the design by varying its dimensions or the incorporated gems to obtain the optimal version, without increasing the workload.
  • Parametric CAD allows variations of the original prototype to be designed without increasing the workload.
  • Style. Parametric CAD produces spectacular results when the design incorporates repetitive mathematical functions such as tessellation, fractality, Fibonacci series, etc. Many of these functions are also capable of giving the piece an organic and irregular character. In principle, parametric CAD is less agile than direct CAD in modeling a certain irregular organic shape (for example, modeling an animal or a certain flower) However, if organic shapes are repeated in a design (even with random or functional variations), Parametric CAD exceeds direct CAD in quality and less workload. Sometimes both techniques can be combined: for example, we can design a flower by direct CAD and tessellate or panel it by parametric CAD.


  • When it is appropriate to model a single version, it is advisable to opt for direct CAD due to its lower workload and therefore lower cost.
  • When it is appropriate to manufacture several versions of a prototype, it is advisable to evaluate the option of the parametric CAD. From a certain number of variations (depending on each design), the parametric CAD will be more economical.
  • In the event that the cost factor is secondary and the aim is to prioritize the aesthetic or technical evaluation of the jewel, it is advisable to consider parametric CAD.
  • For designs that incorporate forms derived from repetitive mathematical functions, it is advisable to prioritize parametric CAD.