Definition
A four-sided figure with all sides of equal length and with opposite angles equal, oriented so that one pair of opposite corners lies on the vertical axis and the other pair on the horizontal axis. In aviation, the diamond shape is used as a symbol on charts and instrument displays to mark specific features such as intersections, reporting points, or other designated locations.
Plain English
A four-sided shape that looks like a square balanced on one of its corners. On charts and instruments, it is used as a small marker to identify particular points or features.
Context Anchor
Used in formation flying, airshow descriptions, military flying, and some training discussions about aircraft spacing and position.
Derivation
The word comes from the Greek 'adamas,' meaning 'unconquerable' or 'hardest substance,' originally referring to the gemstone. Over time it also came to describe the gem's familiar shape, which is how the term ended up on charts and panels.
Why Pilots Care
Knowing that a diamond on a chart marks a specific feature -- such as an intersection or reporting point -- helps a pilot quickly read and follow a chart without confusing it with other symbols.
Intuition Check
Diamond does not mean the aircraft is made of diamond or that the term describes a material. Here it describes the shape made by several aircraft flying together.
Example Sentence 1
The intersection ahead is shown on the chart as a small diamond next to the airway.
Example Sentence 2
The mechanic used a diamond dresser to true the grinding wheel before resurfacing the cylinder head.