In terms of gemstones, there are two main types of style of cut. Faceted and cabochon gemstones. There are other types, such as beads and carved gemstones, and then there are also subcategories, but faceted stones and cabochons are the two types most often used in jewellery and jewellery design.
A faceted demantoid garnet and a green tourmaline cabochon.
In very simple terms, a faceted stone has many flat sides and a cabochon is smooth. Faceted stones are more popular for transparent stones and cabochons are more popular for opaque or translucent stones. Although you can find most stones in both faceted or cabochon shapes these days.
For instance, 99.999999999% of diamonds are faceted, this is because most diamonds used in jewellery are transparent and you want them to reflect light and sparkle, whereas an opaque stone like Malachite is usually cut into a cabochon or bead.
As a general rule, faceted stones sparkle more and cabochons have a nice colour.
Because a faceted stone has many flat sides (facets) which have to be carefully aligned and polished, they take longer to cut and are generally more expensive. When a stone is dug out of the ground, it is assessed for its colour and clarity. If the stone has a good enough colour and is free of natural inclusions then it is worth investing the time and money faceting it, as the end result will be worth the time and money spent, in monetary terms.
If the colour is good but the stone has many cracks, fissures or bubbles (inclusions) then it is more likely to be cut into a cabochon because these natural inclusions will mean the stone will not reflect as much light. This means it’s not worth spending the time faceting the stone, however you can still use it in jewellery if it shaped and then polished into a cabochon.
If the stone has both poor colour and clarity then it could be made into a bead or used industrially.
There are definitely exceptions to this rule. If you find a large, smooth gemstone with good colour and clarity then it could be a good idea to make a cabochon out of it to avoid wasting a lot of material.
Faceted Gemstone Shapes
There are an almost infinite amount of faceted gemstone shapes, with more being added all the time. The most common is the round brilliant cut, this cut has 57 facets and was developed to maximise the sparkle of diamonds, though it can be used for other gemstones.
