|Portrayed by||Jaye Jacobs|
|First Appearance||Series 7 Episode 11|
|Last Appearance||Series 8 Episode 19|
|Cause/Reason||Resigned after slapping Barry Barry|
|Born||8th July 1979|
|Occupation|| Deputy Head |
|Spouse(s)||Jez Diamond (2011 - 2012)|
Sian Diamond is a hit in her role as Science teacher and Deputy Head at Waterloo Road. At first she was devastated not to be working under Karen Fisher 's leadership. Behind the science goggles is an intelligent, sparky and sexy woman, capable of making science appealing to the masses. She worked with Michael Byrne, her boss, at his previous school where the two were once romantically linked. She was married to Jez Diamond , but the pair divorced and Sian was left in custody of her step-children.
Jez was both Sian's husband and colleague. Their relationship started off as a secret affair, as Jez was already married with two children, Zack and Madi . They continued to be in a relationship when everybody found out and later married. The couple then moved to Waterloo Road where their differences began to show, the main one being that Jez was prepared to show his affection towards his wife in front of everybody, whereas Sian was more open to the idea of keeping the affection in the comfort of their home.
Sian started to grow closer to Michael, who was previously in a relationship with her. Eventually, the two begin an affair, of which Jez is oblivious to and just thinks he and Sian are just growing apart. When Jez finds out about the affair, he is in pieces; he truly loved Sian and was destroyed that she didnt feel the same way about him. This resulted to him being suspended after punching Michael,who also happened to be his boss. Jez planned to move to Ireland, removing Zack and Madi from school. However, Sian chases him and the couple roconcile and stay in Rochdale. Jez then believes they are stronger than ever and tells Sian that he wants children of their own. Sian agrees, but secretly goes on the pill to prevent this from happening.
Sian ends her marriage with Jez, explaining they were "fighting a losing battle". She also revealed that she lied about wanting to have a baby, therefore the marraige ended and Jez moved out, but Zack and Madi stayed with Sian. Jez then resigned from Waterloo Road and decided that, whilst the kids stayed with Sian, he would look for a job near where their mother stayed so that, when Zack and Madi moved back in with their mother, he would be around more often.