Stone shapes and how they change a jewellery CAD model
The stone's shape decides the seat, the prongs and even the look of the ring. A model built for a round stone cannot be switched to a marquise by just swapping the stone.
Round
The simplest and most common. It sits evenly in four or six prongs, with a seat that is the same all the way around.
Oval
Elongated, so it lengthens the finger. The prongs are usually placed at the four corners of the long axis.
Marquise and pear
These have points that are easy to chip. The prongs at the points are normally V-shaped or larger. Our marquise ring renders show a six-prong setting built for this.
Emerald and other step cuts
Rectangular with cut corners. They show clarity well, so settings are kept simple, and corners are protected with prongs or tabs.
Cushion
A rounded square, with a seat that follows its curves.
What to share
Tell your designer the shape and exact size in millimetres, including length and width for non-round stones. The stone seat is built from those numbers.
Frequently asked questions
Can I change the stone shape later?
Usually the setting must be rebuilt, so it is best to confirm the shape before modelling.
Which shapes need the most protection?
Stones with points or corners, such as marquise, pear and emerald, need prongs that cover those areas.
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