Why set black diamond earrings in 14k gold? Precious metals enjoy the sturdiness required so that earrings of high value endure. Black diamonds, especially those that form part of a cluster design require a precious metal that is fairly hard as well as being of high quality. The more intrinsic and complex the design is, the harder the metal should be.
For example, the Destino Jewellery range of cluster black diamond earrings are set using 14k white gold. The precious metal 18k white gold could not be used for this design due to the softness of the metal. If a metal is classified by the product designer as being too soft, this means there is a danger that the diamonds will not be secure and therefore will not hold within the grooves and settings of the jewellery piece.