The term "Lydian stones" usually refers to a type of gemstone that comes from the ancient kingdom of Lydia. However, there are a variety of synonyms that can be used to describe similar gemstones. For instance, one might use the term "lydite" to describe any stone that has a similar appearance or properties to Lydian stones. Other synonyms might include "sardonyx," "carnelian," or "chalcedony," depending on the specific characteristics of the stone. It's important to note that while these terms might be interchangeable in some contexts, they may have distinct meanings or uses in others, so it's always a good idea to do your research before using any specialized terminology.