When faceting gemstones, there are many shapes and forms to choose from. What shape the gem is cut into mainly depends on the material and preferences of the cutter, formally known as a lapidary. All ruby rough falls into three categories: carving-grade, cabochan-grade, or faceting-grade. There are finer details of quality that people cutting and treating ruby rough need to be aware of, but the exact terms and grades vary between countries.
The basics are:
Carving-grade rubies are typically opaque to translucent and not very valuable when uncut. These types are literally used for carving and patterns, and are where you will find the most unique and interesting designs.
A famous example of carving-grade rubies (and sapphires, and emeralds) is in the Cartier “Tutti-Frutti” designs. Here are a couple examples of Tutti-Frutti jewelry (they made jewelry other than bracelets in this style too).
R10001 | medium | play | left | “Ruby ID: R10001 – Weight: 1.23 Carats – Origin: Mozambique”
Graded higher than carving rubies are cabochons. Cabochons range in transparency from translucent to fully transparent, and are cut into rounded forms like domes by definition.
Star rubies are always cut into a cabochon shape in order to show the star, as otherwise it is not visible.
In comparison, cabochons and especially star rubies appear a little smaller for their carat weight. As a principle of geometry, rounded forms hold the most weight relative to the visual space they fill up.
Stars in rubies are especially prized and scarce in good quality. When their star is bright the color is typically a bit muddy, and when the color is great the star is weaker. Finding a balance of these properties is very difficult.
R11211 | medium | play | right | “Ruby ID: R11211 Weight: 1.58 Carats Origin: Mozambique”
The most prized quality of rubies is facet-grade, showing very few inclusions. They are also the rarest types of rubies, and do not like to grow to sizes lapidaries can get more than 1 carat from.
Their cuts are usually a variation of a brilliant cut on top, with a modified step cut on the bottom. Other types of cuts are possible too, but they usually are not as versatile with the shape of the rough ruby.
In comparison to what shapes are sculpted from carving-grade rubies, this is a little boring. However, they also show the best sparkle of any gem type.