Utah's Josh Wright has some great piano tutorials for advanced pianists on Youtube. For such a young pianist he is very aware of technique and getting a great sound. In this Youtube tutorial, Josh discusses Pearly sound. Josh's inspiration's for this Pearly Sound is the playing of pianist Murray Perahia. I think this term is fairly common in North America, I don't hear this term used in the UK that often, only by my previous Canadian teacher postgraduate from the Royal Academy of Music.
Josh defines Pearly Sound as a light, clear, beautiful, fleeting sound as opposed to a heavy and muddy sound. Josh demonstrates this concept with a Chopin nocturne, and illustrates the difference and technical approach to achieve Pearly Sound. Enjoy, practise and share!