Diamonds () (French: Carreau) is one of the four playing card suits in the standard French-suited playing cards. It is the only French suit to not have been adapted from the German deck, taking the place of the suit of Bells.

The original French name of the suit is Carreau; in German and Polish it is known as Karo.

In older German-language accounts of card games, Diamonds are frequently referred to as Eckstein ("cornerstone"). In Switzerland, the suit is still called Egge (Ecke i.e. "corner") today. The term "Karo" went into the German language in the 18th century from the French carreau, which goes back to the Latin word, quadrum, meaning "square" or "rectangle".^[1]

The diamond typically has a lozenge shape, a parallelogram with four equal sides, placed on one of its points. The sides are sometimes slightly rounded and the four vertices placed in a square, making the sign look like an astroid.

Normally diamonds are red in colour. They can however be depicted in blue,^[2][3] which is the case for example in bridge (where it is one of the two minor suits along with Clubs). In the official Skat tournament deck, diamonds are yellow or orange, assuming the color of their German-deck equivalent, which are usually golden.

The following gallery shows the diamonds from a standard 52-card deck of French-suited playing cards. Not shown is the Knight of Diamonds used in the tarot card games:

• Ace
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• Jack
• Queen
• King

Four-color decks are sometimes used in tournaments or online.^[4] In such packs Diamonds may be:

• orange in English and German packs
• yellow in American decks and German Skat tournament packs^[5] or
• blue in English and American Poker decks,^[6] French and Swiss four-colour packs.^[5]

The symbol ♦ is already in the CP437 and therefore also part of Windows WGL4. In Unicode a black ♦ and a white ♢ diamond have been defined: