To wear with your evening dress, Sapphire earrings would be a wonderful option as they depict royalty and you are no less than one. According to your choice and what you want to present yourself as; you can go for sapphire studs, sapphire hoops, danglers or drop earrings.
If you buy the sapphire for that particular evening dress doesn’t mean that you can wear it with only that particular outfit. Certainly not, it is only because of their versatility that you bought them, remember? And so you can wear them with many outfits and many places.