Reading through fragrance message boards, I see people referring to scents as HG or Holy Grail. This confused me at first, until I realized what they are talking about. The Holy Grail has several historical connotations, though most people in Christian traditions trace it back to items supposedly used by Jesus at the Last Supper which possessed miraculous powers.
What does this have to do with fragrance? A holy grail fragrance for someone would be their ultimate favorite or the scent which they have been searching for their whole life. To some it might be serious and singular while for others it can vary over time and include many.
In my personal journey, the closest I’ve come to a holy grail is Nasomatto Black Afgano.