Why would one buy a 14k gold ring?

The 14K ring is cheaper than the 18K option, so you will be able to stick to a more resitrictive budget. It is also harder and more durable, meaning a) men prefer it as it won't get damaged when doing manly activities, b) you can put more diamonds in it without worrying about the prongs coming loose and the diamond falling out, c) it will last longer because it's more hard-wearing than higher K gold rings.