The school, at which Sarika was the only Sikh student, insists the only jewellery pupils can wear is a pair of plain earstuds and a watch. It allowed for no exceptions to its uniform policy and there was no mechanism for seeking exceptions on cultural or religious grounds, the court heard.
Sarika's counsel, Helen Mountfield, said her client was taught separately for months – "in educational and social segregation during school hours" – for wearing the bangle. She was later excluded for a day, then for five days, before being excluded indefinitely.
Mountfield went on to say that the central legal issue in the case was whether the school's policy had resulted in unlawful discrimination under the 1976 Race Relations Act, the freedom of religion provisions of the 2006 Equality Act and the 1998 Human Rights Act.
"At the heart of the case is a vital question about the extent of the protection to be afforded to the rights to cultural expression of members of minority ethnic or religious groups in the school setting and possibly beyond," she said.
The complainant's lawyers earlier told the court the simple wrist bangle was not a piece of jewellery but a symbol of her Sikh faith.
The judge, Justice Stephen Silber, was shown a photograph of the England spin bowler Monty Panesar wearing a kara. The judge said he wanted to examine one of the bangles during the hearing, which is scheduled to run for three days.
Lawyers for Sarika also referred to a House of Lords decision 25 years ago that found that a Sikh boy was subjected to indirect race discrimination in being told he could only attend a school if he cut his hair and stopped wearing a turban.
Since being excluded from the Aberdare school, Sarika has enrolled at Mountain Ash comprehensive, where she is allowed to wear the kara. But her mother believes her daughter's education has suffered as a result of the stress associated with the move and the legal case.
The family has handed a petition to the prime minister, Gordon Brown, asking him to intervene in the matter to "show discrimination is totally unacceptable".
Liberty, the human rights group, said it believed Aberdare girls' school had breached race, equality and human rights laws.
Justice Silber said the only issue of fact in the case seemed to be whether Sarika was actually obliged by her religion to wear the kara.
Mountfield said it would not be right for a secular court to decide such an issue.
The case continues.