Since antiquity, gemstones have been an integral part of jewellery. And today, they are still prized for their unique character and intrinsic beauty. But, also since early times, people have found ways to enhance the quality of gemstones, or even create convincing synthetic varieties. At issue now is not so much whether a stone has been treated or created synthetically, but whether this information is disclosed to the customer. While many exhaustive scientific articles have been written on the topic of treated and synthetic stones, this article provides a brief overview of some of the issues involving two varieties of gemstones, quartz and sapphire.