White & Silver Plated Spring Ring Clasps from Rings & Things:
What's the difference between Silver Plate and White Plate?
Silver plate is a thin layer of actual silver. It nicely matches the color of sterling silver. Like sterling silver, silver plate can tarnish. For this reason, it is frequently lacquered to prevent or slow tarnish.
White plate is the "silver" color most often seen on costume jewelry and base-metal findings. It is generally grayer, but more durable, than silver plate. This plating is typically an imitation rhodium made of copper, tin, and zinc. (Older white plated items usually contained nickel, but that has been heavily phased out over the last few decades.)