All of the gemstones offered in our jewelry are naturally occurring and NOT synthetic or simulated gemstones unless otherwise clearly indicated in the item specifications, for example, cubic zirconia. It is of note to add that the overwhelming majority of natural rubies, sapphires, aquamarine, tanzanite, topaz, tourmaline, amethyst, and citrine available on the market are subjected to heat treatment under high heat in a kiln to intensify their color and remove natural impurities and imperfections, which is a practice that has been going on for centuries. Gemstones that have not been enhanced in this way are extremely rare and command high prices. Heat treatment is a stable and permanent enhancement which completes a process that nature started, enhancing a gemstone to beautiful and intense colors, and is not done by jewelers like us, but by the gemstone miners/producers and cutters themselves. The jewelry industry completely accepts heating as an acceptable and permanent treatment for corundum (rubies and sapphires), aquamarine, amethyst, and other gemstones. Please note that we do NOT sell jewelry with fissure filled or fracture filled gemstones, nor do we offer diffusion treated (dyed) or laser drilled gemstones as we feel that these treatments are too extreme and compromise the stability and durability of a gemstone. You may read more about gemstone enhancement on the American Gem Trade Association website here: http://www.agta.org/gemstones