An octagonal ring refers to a ring that has an eight-sided or octagonal cross-section. This can be found in various applications, including jewelry, industrial gaskets, and even some types of abacus jewelry. 

Here's a more detailed look at different types of octagonal rings:

1. Octagonal Ring Joint Gaskets:

• These are metal gaskets with an octagonal cross-section used for sealing flanges. 
• They are known for their radial self-tightening seal and are often used in refineries and other industries where corrosion resistance is crucial. 
• Octagonal ring joint gaskets are a type of Ring Joint Gasket (RTJ) and can be used with flat-bottom grooves on flanges. 

2. Octagonal Ring Jewelry:

• Octagonal rings can be made of various materials like stainless steel and are often designed with unique aesthetics, like the one found on the Acardi website.
• The eight-sided shape can be a design element, adding a distinctive touch to the ring. 

3. Abacus Ring Jewelry:

• Some abacus jewelry pieces, which are often used as pendants or charms, may also feature octagonal shapes or octagonal elements

4. Octagonal Engagement Rings:

• Octagonal diamond cuts or hexagonal engagement rings can also be referred to as octagonal
• The hexagonal shape is a symbol of balance and harmony. 

In summary, an octagonal ring can refer to a ring with an eight-sided shape, which can be found in various contexts, from industrial gaskets to jewelry, with each application having its unique features and purpose.