Leopard is a pattern and color mutation. The leopard tends black in the pattern.

So for your Leopard Ivory example. The Leopard changes the pattern in the Ivory, which would usually go unnoticed since the Ivory is such a strong color mutation. However, since the leopard adds "black" to the patter, think darkness, this is why the purple patterns POPS in a Leopard Ivory...



.... I think.