(IDEX Online) - Lightbox has been testing out lower prices for its lab grown diamonds.It says its Standard quality stones have been discounted from $800 a carat to $600 and its Finest range of higher quality lab growns have been reduced from $1,500 a carat to $1,000.But the De Beers-owned company says it will retain the linear pricing policy - a fixed cost per carat - which it has promoted since its launch in October 2018."The test for these prices for the Standard products was only for loose stones, while the test for these prices for the Finest products was for both loose stones and set jewellery," said a De Beers spokesman."The test focused on ensuring Lightbox reflects prevailing LGD sector dynamics."Lightbox Standard diamonds have remained at $800 a carat since they were introduced over four years ago, during which time lab grown prices generally have plummeted.Pic of Lightbox Basics earrings, courtesy Lightbox.