* Quality of the Ruby: High-quality rubies, especially those with excellent clarity and minimal inclusions, will have a natural luster and shine.
* Cut and Polish: A well-cut and polished ruby will reflect light effectively, making it appear shiny. Poorly cut or unpolished rubies can appear dull.
* Surface Condition: Rubies can appear dull if their surface is scratched, dirty, or coated with oils.
* Treatments: Some treatments, while enhancing color, can sometimes affect the luster of the ruby if not properly executed.
In summary, a good quality ruby that is well-cut, polished, and clean will be shiny. A low-quality ruby, or one that is poorly cut/maintained, will be dull.