The Queen of Diamonds (Q♦) and King of Diamonds (K♦) are representative of a lady and a gentleman.

if the Heart figures indicate people that are close to the querent, the Diamond figures show other people, usually unrelated (except when they represent relatives by marriage.)

In general, they can also stand for people who have wealth or power over the querent, although usually not legal power, as would be the case with Spade cards. With Diamonds we deal with money or knowledge, so they are often a boss, a professor, someone knowledgeable, a specialist doctor, etc.

In love readings, they are neutral. They indicate other people influencing the situation. They can also stand for third parties, or, when the querent is the third wheel, the official partners, especially if there is no love between them and the querent’s partner anymore. Broadly, Diamonds don’t love. This doesn’t mean they actively hate, but their primary loyalty is not to their heart. Keep in mind, though, that just because a partner shows up as a Diamond, it doesn’t mean the story is going to end. Plenty of people stay in relationships out of habit or for questions of interest (and interest must be construed broadly. Even children are a question of interest, as they may give some people a reason beyond love to stay together). Also, unlike Spade cards, Diamonds are usually not actively malicious or aggressive, unless they are surrounded by cards that say otherwise.

In material readings the two Diamond figures are more positive, as they signify wealthy people. This is especially good if the querent is looking for a job–the presence of a wealthy person together with appropriate cards, can indicate finding employment, i.e., a wealthy person to work for. Traditionally this is especially true for the King of Diamonds, but nowadays it may happen with the Queen as well.

Even when they don’t represent people (and this is very rare), the two cards stand for wealth: the Queen indicates increase of wealth, and the King indicates the manipulation of wealth, including commerce, banks, financial institutions and similar things.

Psychologically the cards denote a practical mindset, which can become callous materialism with negative cards, or ability to help and find practical solutions with good cards.

Combinations:

Q/K♦ + 9♦ = an influencial man or woman will play an important role

Q/K♦ + 3♣ = a married man or woman (but he or she doesn’t love her partner)

Q/K♦ + A♥ = it can be a wealthy family member or a distant relative, but depending on the context it can also be a landlord/lady, broadly it shows a homeowner

Q/K♦ + 4♦ = if the Face card doesn’t represent a person, it indicates a wealthy deal

A♠ + K/Q♦ = traditionally a divorced person, but take the context into account (if it were Q/K♠, a widow or widower)