This question does not make sense, especially under geology. And where can you get a natural blue rose from anyway?
It is a proverb goes some thing like this "A ROSE IS A ROSE IS A ROSE, by any name it is still a rose". You already have one good answers and a few more may come but here is my take on the sentence or saying. Can have few good meanings and few bad or...
Lustre is a soft glossy paper, normally use for portraits. Metallic is used very shiny like foil. It is used more for landscape and "artsy" type photos. Get a photo done in one of each and you'll see. You can make and Andy Worhol like pic with the me...