A haughty, jealous, wicked and promiscuous woman, the Queen of Diamonds represents, isolated, your enemy.
However, followed by some cards, its significance is an excellent omen. See the exceptions to this.

This card has on the right a
Spade ♠: Bad intentions of a mean blonde.
Heart ♥: Happy marriage in all respects. Satisfaction in your home.
Diamond ♦: No meaning; card is null.
Club ♣: Gossip, chatter.

Having on the left a
Spade ♠: A slanderous woman and bad morals whose bad intentions you must fear.
Heart ♥: Sincere friend.
Diamond ♦: A slander that will not cause you any harm or trouble.
Club ♣: Jealous, bitter and somewhat thieving woman.

EXCEPTIONS.
Between two aces: Your enemy will come to see you.
Between two cards of the same value: Delayed travel.
Between two spades (seven, eight, nine, ten): Death of a loved one. Revenge and injustice.
With the Eight of Hearts: A girl who has been cheated in love. If Eight of Hearts is touching the Queen of Diamonds, the other card on the right or left does not have any meaning.
With the Queen of Spades: Divorce, widowhood, tears, pain.
With the Jack of Clubs: Stable, happy marriage or sincere friend.

Happy boyfriend, Sincere lover, Slightly dangerous flatterer, Friendly, enterprising, skillful, brave young man; that is the meaning of this card taken in isolation.
This Jack or, better to say – Valet – has many particular meanings that are more or less favourable.
Isolated, pulled from a deck by a young girl or woman, he represents her fiancé, a dark, honest and good young man; but if he is between two spades, his family and friends will oppose the marriage. It will take place anyway, despite all the resistance.
For a young man, he represents his more successful and wealthier rival; but between two heart cards, this rival will be ousted.
For a divorced person or a widower, it’s the announcement of his/her next marriage.
Finally, by any other person, this card ensures complete success in everything they would do.

Having on the right a
Spade ♠: You will meet a young man who has just become rich or famous. This is your chance. Don’t waste it.
Heart ♥: An OK, but not great boyfriend or girlfriend. You can do better in love. However, if he or she is generous in bed and thinks of you, this omen might be misleading. Count all the heart cards that you draw. If you get many – maybe the other cards are trying to tell you something better about your Jack of clubs.
Diamond ♦: Wrong idea. Whatever you are stubbornly convinced and arguing about – take a second look.
Club ♣: Difficulties. – Delay of a marriage due to insufficient wealth or uncertain career.

Having on the left a
Spade ♠: New acquaintance of a pretty brown (brunet) boy, but very silly, although believing himself to be spiritual. Call spade a spade, and call stupid a stupid.
Heart ♥: Discreet love. – Beneficial friend.
Diamond ♦: Visit of a “bon vivant” friend, who will bring you joy and happiness.
Club ♣: Complete success in any business decision that you are agonising about.

EXCEPTIONS.
Between two Spades: Delayed marriage which will only take place after meeting and gaining the favour of the parents.
Between two Hearts: Rivalry that will not be fatal, but very very damaging. If you know who your rival is – strike first.

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.