Stir together sour cream and creme fraiche in a serving bowl. Gently stir in caviar and 2 tablespoons chives until well combined. Cover, and refrigerate for 1 hour (or up to 1 day).
Sprinkle the dip with caviar and remaining 2 teaspoons chives for garnish. Set serving bowl in a larger bowl filled with ice. Serve immediately with root-vegetable chips.
This dip tastes best when chilled for at least one hour before serving.