Isolated, the Jack of Diamonds represents the postman or, better said, the messenger. It also symbolizes a young soldier or an unfaithful servant (assistant, employee); sometimes a young blond man, traitor and of bad morals.
If the consultant is a young man, it is the announcement of new lovers.
If it is a young girl or a single woman, it is the certainty that, soon, a suitor will make himself known; he will be blond and pretty boy.
If, on the contrary, the consultant is married, he will soon learn of a somebody’s else marriage; but this card, surrounded by it, has many and varied meanings.

The Jack of Diamonds with a
Spade ♠: Treachery, infidelity.
Heart ♥: Certainty of marriage and news of birth.
Diamond ♦: Young risk-taking man, adventurer of misconduct.
Club ♣: Somebody will ask to borrow money from you.

Having on the left a
Spade ♠: A dark man you have every reason to fear.
Heart ♥: Love. Letter coming soon.
Diamond ♦: Null card.
Club ♣: Money that will be lost. Theft.

EXCEPTIONS.
The Jack of Diamonds, with the
King of Diamonds: News from a young adventurous man.
Between two sevens: News of a pregnancy.
Touching the Ten of Diamonds: Distant journey. (The other card touching it becomes null and void.)
Touching the ace of Clubs: News of an inheritance. (The other card touching it becomes null and void.)
Between two face cards: deceit, treachery, infidelity.
Between two aces: The Jack of Diamonds says nothing; he is absolutely silent.

An excellent card that, which in isolation means satisfaction, great joy, success.
Anything that causes you pain is reversed or mitigated by this happy card.
Only one exception makes it less favourable; it is when it is placed between two Aces or two cards of the same rank.

Having on the right a
Spade ♠: A short-lived pleasure.
Heart ♥: Satisfaction in love. – Loyalty.
Diamond ♦: Unexpected happiness.
Club ♣: Success in all your business endeavours.

Having on the left a
Spade ♠: Victory in a dispute or court trial.
Heart ♥: Great joy. – Fulfilment of all your desires.
Diamond ♦: Pleasure trip. Holiday trip that will be very enjoyable. Love adventure involving a trip.
Club ♣: Reconciliation with a friend.

EXCEPTIONS.
The Nine of hearts placed between two aces means: Fall or failure without any serious damage.
Between two cards of the same value: Frustrated pleasure. – A friend’s departure. Cooling of an intimate relationship.

Young dark man, fake, mean and treacherous.
While declaring his friendship, he meditates inwardly on betraying you; his morals are light, his associates deplorable.
Very talkative, he easily discloses to anyone what you have entrusted to him in good faith; even the most serious things he has sworn not to say. He does not hinder himself in any way to perjure himself, as long as it can attract him a profit, however small it may be.

This Jack having on the right a
Spade ♠: Bad acquaintance. – False friend to oust.
Heart ♥: Somebody will want to date you and get into a relationship with you; just say “no” to him. – Bad words from a young brown man.
Diamond ♦: Slander in the city.
Club ♣: Abuse of trust. – Flatterer to be feared.

Having on the left a
Spade ♠: Unscrupulous. – A young dark man will try to seduce you. He is not as powerful as the King of spades. If you recognise him, you should have no trouble of resisting him.
Heart ♥: A joyful meeting that will go wrong towards the end of the evening.
Club ♣: Jealousy. – Discomforts.

EXCEPTIONS.
Between two cards of the same value: Bad intentions in a business of family meeting.
Between Aces: Your enemy will go to jail.
With the Queen of Spades: Criminal attempt; the other card touching the Jack of Spades is void; it does not speak.
Near the Eight of Spades: Violent death of a friend; the other card touching the Jack of Spades is null; it does not speak.