Pearl is a soft white shade with a wonderful feel. The photo below show the difference between the leather and silk materials. They’re nearly the same, though the silk has its trademark pearlescent sheen.
Here is a custom box made using both materials. Leather on the cover, silk for the sidewalls.
I’m also asked about washing these white colors. The leather is a tough material. It will resist liquids and you can clean it with a damp rag without worry. The silk should not come in contact with liquids (this is true with all bookcloths). I recommend a soft brush or lint-roller to clean bookcloth. No lint-roller? Masking tape works just as well.