Black is associated with power, authority, mystery, formality, rebellion, and sophistication... Just to name a few. 

 Gold represents luxury, love, wisdom and magic. 

Bones symbolize morality, rebirth and therefore a medium that connects life and death. 

What I find most interesting is many people are drawn to bones of all kinds. It is common to see posts talking about finds in the woods or seeing bones take up space in someone's home. 

To be a bone collector is quite intriguing. I love hearing the draw for others, the drive to collect.