Your question seems to relate more to the printing process than to CorelDraw.
I never heard of laser or inkjet printers that use silver ink. Such printers output color as process colors (CMYK) or RGB. They print silver as gray. Real silver is a spot color. It is a metallic ink PMS 877. You can find it in the "Palettes" section of the color fill menu.
I use a commercial printer when I need something printed in silver ink. 4Over is a printer that will print four-color process plus silver as a spot color.
Shades of gray (or tints) are shown in 10% increments in the color palette on the right side of your drawing window. You can change that value to any number via the "Fill" icon on the left side. Still, you will only get a shade of gray, not real silver. Silver ink actually contains metallic particles that give it a shine.