Question about my demon-wearing-a-cat-suit's breed

I don't care in the slightest what the answer is, I'm just curious. I was told that she's a ragdoll x russian blue breed. Her siblings had blue pelts so no one wanted her because she was black. She's also pretty big, she's not overweight according to the vet, but she's MUCH bigger than my bf's feral-born tabby tom cat. Her name is Jerma, and she is I guess medium fur length?