Yvonne Léon is constantly sourcing inspiration from local flea markets - the Saint-Ouen in Paris is one of her favorites. Handcrafted in France from 18-karat gold, this ring has an 8.00-carat agate heart that's framed by an intricately engraved border, and is punctuated with 0.02-carats of diamonds. Complement the bold red hue with a nude manicure .