The sapphire was thrown into the river and Evadne duly cursed
Also known as The Gem of Sorrow, This haunted object does not bring accidental death but instead it brings misfortune and deep sorrow. The mysterious stone is rumored to have been stolen by a British solider from the Temple of Indra (the Hindu god of war and weather) in Kanpur, India, during the Mutiny of 1857.
The sapphire was then thrown into the river, with Evadne cursing Tommy Shelby in retaliation for her daughter's death. She vowed that any daughter of his would also die at the age of seven.
In the second episode of the third season, Tommy gave the sapphire in a necklace for his beloved wife Grace Shelby (Annabelle Wallis) to wear at the dinner for the Shelby Charity Foundation. At the dinner, Tatiana informs Tommy that the sapphire being worn by Grace was "cursed by a Gypsy".
You gave a sapphire to a woman called Bethany Barwell," Esme tells Tommy. "She gave the stone to her sister, Navadni Barwell. Navadni put the stone around the neck of her daughter and straight away the girl began to cough. She died that night, seven years old," she continues.
In season six, that ambiguity was replaced with certainty. The sapphire was indeed cursed, Esme Shelby-Lee tells Tommy.
Tommy gave the sapphire to Bethany Barwell, who took it to her sister Evadne, who in turn put it around her daughter's neck. 7-year-old Connie died the next day, and according to Esme, it was Evadne that put the curse on Tommy to lose his daughter when she turns seven.
Ruby may be warning of a coming devil (Tommy, perhaps, or the fascist tide in Europe). Or, as some fans speculated, the warning is that the daughter of the devil will die. If the devil is Tommy, then the daughter is Ruby.
When Ruby initially began to become ill and dileious, Lizzie told Tommy that she spoke the Romani words "Tickna mora o'beng". This sent Tommy into a panic and he immediately rushed home.
Eventually, Lizzie has had enough, with him sleeping with Diana Mitford being the last straw. She informs Thomas that she is leaving him. He surprises her by letting Charles go with her.
That whisper is the semi-public admission that Tommy is shaking his blood-stained hands with Duke, and expecting him to carry on his dark deeds.
If you've ever noticed that Shelby never eats on the show, that's because it was an accidental choice that later turned into an intentional decision. Once fans noticed this quirk, Murphy and Knight decided to turn it into a “Tommy thing,” which added to the character's obsessive industriousness.
Lizzie officially reached the end of her tether after discovering Tommy had slept with Diana Mitford and decided to leave him. Still distraught over the death of her daughter Ruby, she's surprised when Tommy's son Charlie asks to join her instead of staying with him.
The Man With Green Eyes and The Grey Man, despite a lot of speculation, are actually the same person- Dr Holford. He only appeared once or twice in the series beforehand, his most memorable scene was giving Tommy his diagnosis, so he largely flew under the radar.
The Hope Diamond
Arguably the most famous and most cursed precious gemstone in history, this 45.52-carat sparkler has a long and storied past. The Hope Diamond has been blamed for a laundry list of tragedies, including but not limited to: beatings, stabbings, murder, insanity, and suicide.
The scene shows that Polly chooses to take Michael's side in the conflict before she dies. The use of Michael's blood also implies that Polly set the curse upon Tommy, as she has previously claimed a connection to the supernatural, seemingly communing with spirits.
Lizzie added that Ruby kept seeing a 'man with green eyes' causing Tommy to panic.
Tommy Shelby's upbringing around Romani mysticism led him to believe that Ruby's illness is a curse, leading him to call Esme. Furthermore, he believes that her hearing voices and having visions is evidence of second sight—a gift that his Aunt Polly also shared.
Ruby Shelby was the daughter of Thomas and Lizzie Shelby and half-sister of Charles Shelby. She was named by her paternal great-aunt, Polly Gray.
So, Tommy stands in front of the carriage in which Ruby's coffin sits, speaking to his friends and family about his deceased daughter. He says that in Ruby's memory, “things will change.” He wants to make peace and do good for his daughter.
– The Romani gypsy words spoken by Ruby in her fevered state appear to be “Tikno mora o beng o beng”. In this English/Romani dictionary, 'tikno' means child or small, 'mora' or 'maura' means to slay or kill, and 'o beng' means 'the devil'.
Yes, it appears that Doctor Holford was the 'Grey Man'. After numerous warnings from a sick Ruby Shelby of a “grey man” and “the man with green eyes" and repeated the Romani phrase “tickna mora o'beng”.
He did warn Bethany about the stone, but she gave it to her sister nonetheless. Evadne then put that stone on her daughter's neck, who died the same day at the age of seven. After that, Evadne cursed Thomas Shelby to get vengeance.
Polly goes to a Romani medium seeking news of the children who were taken from her by the Parish in infancy. The medium tells her that her daughter has died. Thomas kills a blacksmith before picking up his brothers, Arthur and John to go to London.
However, Billy Grade (Emmett J. Scanlan) was revealed to be the informant after he picked up the phone and tipped off the IRA. The IRA took out Barney as well as Aberama Gold (Aidan Gillen) and Polly Gray (Helen McCrory) to thwart the plan and also to punish Tommy.