(IDEX Online) - Brilliant Earth has ditched a promotional offer for "free diamond earrings" following a challenge from rival Blue Nile.It voluntarily pulled ads after complaints that the diamonds were lab-grown rather than mined, and the "free" offer was only available for a very limited time.Brilliant Earth, the US-based "ethical jeweler", had used the phrases "Free Diamond Earrings" and "One Day Only!" to advertise the promotion.Online jeweler Blue Nile, based in Seattle, USA, complained to the watchdog National Advertising Division (NAD), part of BBB National Programs.Brilliant Earth pre-empted an NAD ruling by agreeing to withdraw the promotion.The company "believes that the challenged advertising claims were substantiated," said the NAD in a press release, and told them "it no longer plans to run the challenged claims in any medium, and therefore agreed to voluntarily and permanently discontinue them".Pic courtesy Brilliant Earth