We just got a part-Siamese kitten last week (I think it's a "ragdoll"). He's already in charge of things.
Is she "pointed"? Is she slim? Is she active? Is she extremely vocal?
Most Siamese crosses are either black (if there's no Siamese on one side) or "pointed" (if there's Siamese on both sides), usually with tabby or tortie points.
But the voice seems to be dominant, and it's absolutely unmistakeable.