diamond

noun

• 1a precious stone consisting of a clear and colourless crystalline form of pure carbon, the hardest naturally occurring substance: [as modifier]:a diamond ring
• a tool with a small diamond for cutting glass.
• (a diamond) British informal an excellent or very special person or thing:Fred’s a diamond

Diamonds occur in some igneous rock formations (kimberlite) and alluvial deposits. They are typically octahedral in shape but can be cut in many ways to enhance the internal reflection and refraction of light, producing jewels of sparkling brilliance. Diamonds are also used in cutting tools and abrasives

• 2 [often as modifier] a figure with four straight sides of equal length forming two opposite acute angles and two opposite obtuse angles; a rhombus:a sweater with a pale-blue diamond pattern
• (diamonds) one of the four suits in a conventional pack of playing cards, denoted by a red diamond.
• a card of the suit of diamonds: she led a losing diamond

• 3the area delimited by the four bases of a baseball field, forming a square shape.
• a baseball field.

• 4 [usually as modifier] a railway crossing in which two tracks cross over each other at an acute angle: diamond crossings