Simply put, we choose the metals that best capture our nautical knots. 18k yellow gold contains a larger gold to alloy ratio, which creates a lustrous piece with a deeper, richer hue than 14k yellow gold. 14k rose gold provides a brighter color with a stronger pink hue than 18k rose gold.If you prefer 14k yellow gold or 18k rose gold, please email support@preciousknots.com and we will happily fulfill your wishes!