A British Airways employee suffered discrimination at work over her Christian beliefs, the European Court of Human Rights (ECHR) has ruled.
Nadia Eweida took her case to the ECHR after BA made her stop wearing her white gold cross visibly.
The court said BA had not struck a fair balance between Ms Eweida's religious beliefs and the company's wish to "project a certain corporate image".
It ruled the rights of three others had not been violated by their employers.
But they said Ms Eweida's rights had been violated under Article 9 of the European Convention on Human Rights.
The four Christians had brought cases against the UK government for not protecting their rights but ministers, who contested the claims, argued that the rights of the employees were only protected in private.
Ms Eweida, 60, a Coptic Christian from Twickenham in south-west London, told the BBC she was "jumping with joy" after the ruling, adding it had "not been an easy ride".
British Airways said its uniform policy was changed in 2007 to allow Miss Eweida and others to "wear symbols of faith" and that she and other employees had been working under these arrangements for the last six years.
It said Ms Eweida did not attend work for a period of time in 2006 while an internal appeal was held into her refusal to remove her cross but she remained a British Airways employee.
The British government was ordered to pay Ms Eweida 2,000 euros (£1,600) in damages and 30,000 euros (£25,000) costs.
A tribunal decision was upheld by the Court of Appeal and the Supreme Court in the UK before she took her case to the ECHR.
Prime Minister David Cameron said he was "delighted" that the "principle of wearing religious symbols at work has been upheld", adding that people "shouldn't suffer discrimination due to religious beliefs".
The other cases involved nurse Shirley Chaplin, 57, whose employer also stopped her wearing necklaces with a cross, Gary McFarlane, 51, a marriage counsellor sacked after saying he might object to giving sex therapy advice to gay couples, and registrar Lillian Ladele who was disciplined after she refused to conduct same-sex civil partnership ceremonies.
The four had made individual applications to the ECHR after losing separate employment tribunals but their cases were heard together.
They argued their employers' actions went against articles 9 and 14 of the European Convention on Human Rights, which protected their rights to "freedom of thought, conscience and religion" and prohibited religious discrimination.
Ms Ladele was disciplined by Islington Council, in north London, after saying she did not want to conduct same-sex civil partnership ceremonies. Her lawyers said the service could have been performed by other employees who were prepared to carry them out.
ECHR judges said the council's action was legitimate as it was obliged to consider the rights of same-sex couples.
Mike Judge, of the Christian Institute, which backed Ms Ladele's case, said: "What this case shows is that Christians with traditional beliefs about marriage are at risk of being left out in the cold."
Mr McFarlane, a Bristol relationship counsellor, worked for the Avon branch of national charity Relate but was sacked for gross misconduct in 2008 after saying on a training course he might have an objection to discussing sexual problems with gay couples.
The court said clients of the service where he was employed could not be allocated in accordance with their sexual orientation.
Mr McFarlane told the BBC that the decision in his case was "a regrettable judgment" for all faiths, not just Christians.
Ms Chaplin, from Exeter, was transferred to a desk job by Royal Devon and Exeter NHS Trust Hospital for failing to remove a confirmation crucifix on a small chain, which she had worn to work for 30 years.
The court said the decision was necessary to protect the health and safety of nurses and patients.
She said she thought British Christians would be "devastated" by the ruling.
The three plan to ask for their cases to go to appeal to the Grand Chamber of the ECHR.
Employment lawyers at firm Slater and Gordon said the decision did not change the situation that discriminating against a person purely because of their religion was against UK law.
They said it also showed that corporate image did not trump a person's right to reasonable expression of their religious belief.
Communities Secretary Eric Pickles and the Equalities Minister Maria Miller both welcomed the ruling.
Keith Porteous-Wood, of the National Secular Society, said: "Religious people who feel elements of their job go against their conscience can always find employment that better matches their needs. That is true religious freedom."
Shami Chakrabarti, director of human rights group Liberty, said the judgment was "an excellent result for equal treatment, religious freedom and common sense".
The Archbishop of York, Dr John Sentamu, said the Equality Act "encourages employers to embrace diversity - including people of faith".