I've had a look today but we've got a standard and dark shade on our system. But unfortunately no XSC codes to cross reference to.

I got the book out and had a look though and XSC2741 is jewel violet so thats the one. But that lists no varients. And as Paul said the code on the car should be T4, although the number isn't really that important.

I'd go with standard shade anyway even if they do list others where you get it from.