In contract bridge

Contract bridge

Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

 the minor suits

Suit (cards)

In playing cards, a suit is one of several categories into which the cards of a deck are divided. Most often, each card bears one of several symbols showing to which suit it belongs; the suit may alternatively or in addition be indicated by the color printed on the card...

are diamonds  and clubs . They are given that name because contracts made in those suits score less (20 per contracted trick) than contracts made in the major suit

Major suit

In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...

s (30 per contracted trick), and they rank lower in bidding. In particular, one can make game with a bid of 4 in a major suit, while a bid of 5 is required in a minor. Of the two minor suits, diamonds  rank higher than clubs 

Suit combinations

Fundamentally, there are three ways to divide four suits into pairs: by color, by rank and by shape resulting in six possible suit combinations.

• Color is used to denote the red suits (hearts and diamonds) and the black suits (spades and clubs).
• Rank is used to indicate the major
  Major suit
  In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...
  
  (spades and hearts) versus minor
  Minor suit
  In contract bridge the minor suits are diamonds and clubs . They are given that name because contracts made in those suits score less than contracts made in the major suits , and they rank lower in bidding. In particular, one can make game with a bid of 4 in a major suit, while a bid of 5 is...
  
  (diamonds and clubs) suits.
• Shape is used to denote the pointed (diamonds and spades, which visually have a sharp point uppermost) versus rounded (hearts and clubs) suits.

In the event of widespread introduction of four-color deck

Four-color deck

A four-color deck is identical to the standard French deck except for the color of the suits. In a typical four-color deck, hearts are red and spades are black as usual, but clubs are green and diamonds are blue. However, other color combinations have been used over the centuries.In 1819, J.Y...

s, it has been suggested that the red/black distinction could be replaced by pointed bottoms (hearts and diamonds visually have a sharp point downwards, whereas spades and clubs have a blunt stem).