- colour: natural 100% natural cow leather, goat skin lining, rubber & leather sole Serge is a comfortable, soft oxford shoe. It’s timeless, unisex and smart looking.Serge's perfect for both formal and casual look. Serge comes in options of smooth leather and soft-brushed suede. *Please note that leather is a diversified material, therefore each piece is unique. This leather changes over time, from year to year it darkens and gains nobility.