Why has hair turned a warm copper colour

[Rachel6996]

This is my sister's hair. She is a base 7 with over 50% grey. Today as usual I put some foil highlights through her hair and mixed 7.0 with of 7.1 and put it on the roots and took it through to the ends as she has a lot of warmth in her hair. This is the same colours I always use on her yet today it has turned out a warm almost copper colour. Please see picture attached. Any idea why this has happened? And the quickest way you would correct it without having to darker down the highlights?

 

[ronray]

This is my sister's hair. She is a base 7 with over 50% grey. Today as usual I put some foil highlights through her hair and mixed 7.0 with of 7.1 and put it on the roots and took it through to the ends as she has a lot of warmth in her hair. This is the same colours I always use on her yet today it has turned out a warm almost copper colour. Please see picture attached. Any idea why this has happened? And the quickest way you would correct it without having to darker down the highlights?

It's difficult to see what the issue is in the photo. It doesn't look copper in the picture?
Therer can be a number of reasons why this can happen.
It could be hormones...
It could be different shade in the tube....
It could be mineral deposits in the hair...
Has she moved recently?
Has she changed anything in her haircare regime?
Any changes of medication?